Implement actions (#21937)

Close #13539.

Co-authored by: @lunny @appleboy @fuxiaohei and others.

Related projects:
- https://gitea.com/gitea/actions-proto-def
- https://gitea.com/gitea/actions-proto-go
- https://gitea.com/gitea/act
- https://gitea.com/gitea/act_runner

### Summary

The target of this PR is to bring a basic implementation of "Actions",
an internal CI/CD system of Gitea. That means even though it has been
merged, the state of the feature is **EXPERIMENTAL**, and please note
that:

- It is disabled by default;
- It shouldn't be used in a production environment currently;
- It shouldn't be used in a public Gitea instance currently;
- Breaking changes may be made before it's stable.

**Please comment on #13539 if you have any different product design
ideas**, all decisions reached there will be adopted here. But in this
PR, we don't talk about **naming, feature-creep or alternatives**.

### ⚠️ Breaking

`gitea-actions` will become a reserved user name. If a user with the
name already exists in the database, it is recommended to rename it.

### Some important reviews

- What is `DEFAULT_ACTIONS_URL` in `app.ini` for?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1055954954
- Why the api for runners is not under the normal `/api/v1` prefix?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1061173592
- Why DBFS?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1061301178
- Why ignore events triggered by `gitea-actions` bot?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1063254103
- Why there's no permission control for actions?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1090229868

### What it looks like

<details>

#### Manage runners

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205870657-c72f590e-2e08-4cd4-be7f-2e0abb299bbf.png">

#### List runs

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205872794-50fde990-2b45-48c1-a178-908e4ec5b627.png">


#### View logs

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205872501-9b7b9000-9542-4991-8f55-18ccdada77c3.png">



</details>

### How to try it

<details>

#### 1. Start Gitea

Clone this branch and [install from
source](https://docs.gitea.io/en-us/install-from-source).

Add additional configurations in `app.ini` to enable Actions:

```ini
[actions]
ENABLED = true
```

Start it.

If all is well, you'll see the management page of runners:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205877365-8e30a780-9b10-4154-b3e8-ee6c3cb35a59.png">


#### 2. Start runner

Clone the [act_runner](https://gitea.com/gitea/act_runner), and follow
the
[README](https://gitea.com/gitea/act_runner/src/branch/main/README.md)
to start it.

If all is well, you'll see a new runner has been added:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205878000-216f5937-e696-470d-b66c-8473987d91c3.png">

#### 3. Enable actions for a repo

Create a new repo or open an existing one, check the `Actions` checkbox
in settings and submit.

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205879705-53e09208-73c0-4b3e-a123-2dcf9aba4b9c.png">
<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205879383-23f3d08f-1a85-41dd-a8b3-54e2ee6453e8.png">

If all is well, you'll see a new tab "Actions":

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205881648-a8072d8c-5803-4d76-b8a8-9b2fb49516c1.png">

#### 4. Upload workflow files

Upload some workflow files to `.gitea/workflows/xxx.yaml`, you can
follow the [quickstart](https://docs.github.com/en/actions/quickstart)
of GitHub Actions. Yes, Gitea Actions is compatible with GitHub Actions
in most cases, you can use the same demo:

```yaml
name: GitHub Actions Demo
run-name: ${{ github.actor }} is testing out GitHub Actions 🚀
on: [push]
jobs:
  Explore-GitHub-Actions:
    runs-on: ubuntu-latest
    steps:
      - run: echo "🎉 The job was automatically triggered by a ${{ github.event_name }} event."
      - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by GitHub!"
      - run: echo "🔎 The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."
      - name: Check out repository code
        uses: actions/checkout@v3
      - run: echo "💡 The ${{ github.repository }} repository has been cloned to the runner."
      - run: echo "🖥️ The workflow is now ready to test your code on the runner."
      - name: List files in the repository
        run: |
          ls ${{ github.workspace }}
      - run: echo "🍏 This job's status is ${{ job.status }}."
```

If all is well, you'll see a new run in `Actions` tab:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205884473-79a874bc-171b-4aaf-acd5-0241a45c3b53.png">

#### 5. Check the logs of jobs

Click a run and you'll see the logs:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205884800-994b0374-67f7-48ff-be9a-4c53f3141547.png">

#### 6. Go on

You can try more examples in [the
documents](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions)
of GitHub Actions, then you might find a lot of bugs.

Come on, PRs are welcome.

</details>

See also: [Feature Preview: Gitea
Actions](https://blog.gitea.io/2022/12/feature-preview-gitea-actions/)

---------

Co-authored-by: a1012112796 <1012112796@qq.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: ChristopherHX <christopher.homberger@web.de>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>

options/locale/locale_en-US.ini

@@ -1872,6 +1872,7 @@ settings.pulls.allow_rebase_update = Enable updating pull request branch by reba
 settings.pulls.default_delete_branch_after_merge = Delete pull request branch after merge by default
 settings.packages_desc = Enable Repository Packages Registry
 settings.projects_desc = Enable Repository Projects
+settings.actions_desc = Enable Repository Actions
 settings.admin_settings = Administrator Settings
 settings.admin_enable_health_check = Enable Repository Health Checks (git fsck)
 settings.admin_code_indexer = Code Indexer
@@ -2566,6 +2567,9 @@ dashboard.delete_old_actions.started = Delete all old actions from database star
 dashboard.update_checker = Update checker
 dashboard.delete_old_system_notices = Delete all old system notices from database
 dashboard.gc_lfs = Garbage collect LFS meta objects
+dashboard.stop_zombie_tasks = Stop zombie tasks
+dashboard.stop_endless_tasks = Stop endless tasks
+dashboard.cancel_abandoned_jobs = Cancel abandoned jobs
 
 users.user_manage_panel = User Account Management
 users.new_account = Create User Account
@@ -3249,3 +3253,59 @@ deletion = Remove secret
 deletion.description = Removing a secret will revoke its access to repositories. Continue?
 deletion.success = The secret has been removed.
 deletion.failed = Failed to remove secret.
+
+[actions]
+actions = Actions
+
+unit.desc = Manage actions
+
+status.unknown = "Unknown"
+status.waiting = "Waiting"
+status.running = "Running"
+status.success = "Success"
+status.failure = "Failure"
+status.cancelled = "Cancelled"
+status.skipped = "Skipped"
+status.blocked = "Blocked"
+
+runners = Runners
+runners.runner_manage_panel = Runners Management
+runners.new = Create new Runner
+runners.new_notice = How to start a runner
+runners.status = Status
+runners.id = ID
+runners.name = Name
+runners.owner_type = Type
+runners.description = Description
+runners.labels = Labels
+runners.last_online = Last Online Time
+runners.agent_labels = Agent Labels
+runners.custom_labels = Custom Labels
+runners.custom_labels_helper = Custom labels are labels that are added manually by an administrator. A comma separates labels, whitespace at the start and end of each label is ignored.
+runners.runner_title = Runner
+runners.task_list = Recent tasks on this runner
+runners.task_list.run = Run
+runners.task_list.status = Status
+runners.task_list.repository = Repository
+runners.task_list.commit = Commit
+runners.task_list.done_at = Done At
+runners.edit_runner = Edit Runner
+runners.update_runner = Update Changes
+runners.update_runner_success = Runner updated successfully
+runners.update_runner_failed = Failed to update runner
+runners.delete_runner = Delete this runner
+runners.delete_runner_success = Runner deleted successfully
+runners.delete_runner_failed = Failed to delete runner
+runners.delete_runner_header = Confirm to delete this runner
+runners.delete_runner_notice = If a task is running on this runner, it will be terminated and mark as failed. It may break building workflow.
+runners.none = No runners available
+runners.status.unspecified = Unknown
+runners.status.idle = Idle
+runners.status.active = Active
+runners.status.offline = Offline
+
+runs.all_workflows = All Workflows
+runs.open_tab = %d Open
+runs.closed_tab = %d Closed
+runs.commit = Commit
+runs.pushed_by = Pushed by