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

options/locale/locale_en-US.ini

@@ -747,6 +747,7 @@ access_token_deletion_cancel_action = Cancel
 access_token_deletion_confirm_action = Delete
 access_token_deletion_desc = Deleting a token will revoke access to your account for applications using it. This cannot be undone. Continue?
 delete_token_success = The token has been deleted. Applications using it no longer have access to your account.
+select_scopes = Select scopes
 
 manage_oauth2_applications = Manage OAuth2 Applications
 edit_oauth2_application = Edit OAuth2 Application