Dump github/gitlab/gitea repository data to a local directory and restore to gitea (#12244)

* Dump github/gitlab repository data to a local directory

* Fix lint

* Adjust directory structure

* Allow migration special units

* Allow migration ignore release assets

* Fix lint

* Add restore repository

* stage the changes

* Merge

* Fix lint

* Update the interface

* Add some restore methods

* Finish restore

* Add comments

* Fix restore

* Add a token flag

* Fix bug

* Fix test

* Fix test

* Fix bug

* Fix bug

* Fix lint

* Fix restore

* refactor downloader

* fmt

* Fix bug isEnd detection on getIssues

* Refactor maxPerPage

* Remove unused codes

* Remove unused codes

* Fix bug

* Fix restore

* Fix dump

* Uploader should not depend downloader

* use release attachment name but not id

* Fix restore bug

* Fix lint

* Fix restore bug

* Add a method of DownloadFunc for base.Release to make uploader not depend on downloader

* fix Release yml marshal

* Fix trace information

* Fix bug when dump & restore

* Save relative path on yml file

* Fix bug

* Use relative path

* Update docs

* Use git service string but not int

* Recognize clone addr to service type

docs/content/doc/usage/command-line.en-us.md

@@ -441,3 +441,28 @@ Manage running server operations:
               - `--host value`, `-H value`: Mail server host (defaults to: 127.0.0.1:25)
               - `--send-to value`, `-s value`: Email address(es) to send to
               - `--subject value`, `-S value`: Subject header of sent emails
+
+### dump-repo
+
+Dump-repo dumps repository data from git/github/gitea/gitlab:
+
+- Options:
+  - `--git_service service` : Git service, it could be `git`, `github`, `gitea`, `gitlab`, If clone_addr could be recognized, this could be ignored.
+  - `--repo_dir dir`, `-r dir`: Repository dir path to store the data 
+  - `--clone_addr addr`: The URL will be clone, currently could be a git/github/gitea/gitlab http/https URL. i.e. https://github.com/lunny/tango.git
+  - `--auth_username lunny`: The username to visit the clone_addr
+  - `--auth_password <password>`: The password to visit the clone_addr
+  - `--auth_token <token>`: The personal token to visit the clone_addr
+  - `--owner_name lunny`: The data will be stored on a directory with owner name if not empty
+  - `--repo_name tango`: The data will be stored on a directory with repository name if not empty
+  - `--units <units>`: Which items will be migrated, one or more units should be separated as comma. wiki, issues, labels, releases, release_assets, milestones, pull_requests, comments are allowed. Empty means all units.
+
+### restore-repo
+
+Restore-repo restore repository data from disk dir:
+
+- Options:
+  - `--repo_dir dir`, `-r dir`: Repository dir path to restore from
+  - `--owner_name lunny`: Restore destination owner name
+  - `--repo_name tango`: Restore destination repository name
+  - `--units <units>`: Which items will be restored, one or more units should be separated as comma. wiki, issues, labels, releases, release_assets, milestones, pull_requests, comments are allowed. Empty means all units.