Support scoped access tokens (#20908)

This PR adds the support for scopes of access tokens, mimicking the
design of GitHub OAuth scopes.

The changes of the core logic are in `models/auth` that `AccessToken`
struct will have a `Scope` field. The normalized (no duplication of
scope), comma-separated scope string will be stored in `access_token`
table in the database.
In `services/auth`, the scope will be stored in context, which will be
used by `reqToken` middleware in API calls. Only OAuth2 tokens will have
granular token scopes, while others like BasicAuth will default to scope
`all`.
A large amount of work happens in `routers/api/v1/api.go` and the
corresponding `tests/integration` tests, that is adding necessary scopes
to each of the API calls as they fit.


- [x] Add `Scope` field to `AccessToken`
- [x] Add access control to all API endpoints
- [x] Update frontend & backend for when creating tokens
- [x] Add a database migration for `scope` column (enable 'all' access
to past tokens)

I'm aiming to complete it before Gitea 1.19 release.

Fixes #4300

docs/content/doc/developers/oauth2-provider.en-us.md

@@ -42,7 +42,41 @@ To use the Authorization Code Grant as a third party application it is required
 
 ## Scopes
 
-Currently Gitea does not support scopes (see [#4300](https://github.com/go-gitea/gitea/issues/4300)) and all third party applications will be granted access to all resources of the user and their organizations.
+Gitea supports the following scopes for tokens:
+
+| Name | Description |
+| ---- | ----------- |
+| **(no scope)** | Grants read-only access to public user profile and public repositories. |
+| **repo** | Full control over all repositories. |
+|     **repo:status** | Grants read/write access to commit status in all repositories. |
+|     **public_repo** | Grants read/write access to public repositories only. |
+| **admin:repo_hook** | Grants access to repository hooks of all repositories. This is included in the `repo` scope. |
+|     **write:repo_hook** | Grants read/write access to repository hooks |
+|     **read:repo_hook** | Grants read-only access to repository hooks |
+| **admin:org** | Grants full access to organization settings |
+|     **write:org** | Grants read/write access to organization settings |
+|     **read:org** | Grants read-only access to organization settings |
+| **admin:public_key** | Grants full access for managing public keys |
+|     **write:public_key** | Grant read/write access to public keys |
+|     **read:public_key** | Grant read-only access to public keys |
+| **admin:org_hook** | Grants full access to organizational-level hooks |
+| **notification** | Grants full access to notifications |
+| **user** | Grants full access to user profile info |
+|     **read:user** | Grants read access to user's profile |
+|     **user:email** | Grants read access to user's email addresses |
+|     **user:follow** | Grants access to follow/un-follow a user |
+| **delete_repo** | Grants access to delete repositories as an admin |
+| **package** | Grants full access to hosted packages |
+|     **write:package** | Grants read/write access to packages |
+|     **read:package** | Grants read access to packages |
+|     **delete:package** | Grants delete access to packages |
+| **admin:gpg_key** | Grants full access for managing GPG keys |
+|     **write:gpg_key** | Grants read/write access to GPG keys |
+|     **read:gpg_key** | Grants read-only access to GPG keys |
+| **admin:application** | Grants full access to manage applications |
+|     **write:application** | Grants read/write access for managing applications |
+|     **read:application** | Grants read access for managing applications |
+| **sudo** | Allows to perform actions as the site admin. |
 
 ## Client types