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

services/auth/oauth2.go

@@ -59,6 +59,8 @@ func (o *OAuth2) Name() string {
 }
 
 // userIDFromToken returns the user id corresponding to the OAuth token.
+// It will set 'IsApiToken' to true if the token is an API token and
+// set 'ApiTokenScope' to the scope of the access token
 func (o *OAuth2) userIDFromToken(req *http.Request, store DataStore) int64 {
 	_ = req.ParseForm()
 
@@ -86,6 +88,7 @@ func (o *OAuth2) userIDFromToken(req *http.Request, store DataStore) int64 {
 		uid := CheckOAuthAccessToken(tokenSHA)
 		if uid != 0 {
 			store.GetData()["IsApiToken"] = true
+			store.GetData()["ApiTokenScope"] = auth_model.AccessTokenScopeAll // fallback to all
 		}
 		return uid
 	}
@@ -101,6 +104,7 @@ func (o *OAuth2) userIDFromToken(req *http.Request, store DataStore) int64 {
 		log.Error("UpdateAccessToken: %v", err)
 	}
 	store.GetData()["IsApiToken"] = true
+	store.GetData()["ApiTokenScope"] = t.Scope
 	return t.UID
 }