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

tests/integration/api_admin_org_test.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"testing"
 
+	auth_model "code.gitea.io/gitea/models/auth"
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
 	api "code.gitea.io/gitea/modules/structs"
@@ -20,7 +21,7 @@ import (
 func TestAPIAdminOrgCreate(t *testing.T) {
 	onGiteaRun(t, func(*testing.T, *url.URL) {
 		session := loginUser(t, "user1")
-		token := getTokenForLoggedInUser(t, session)
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeSudo)
 
 		org := api.CreateOrgOption{
 			UserName:    "user2_org",
@@ -54,7 +55,7 @@ func TestAPIAdminOrgCreate(t *testing.T) {
 func TestAPIAdminOrgCreateBadVisibility(t *testing.T) {
 	onGiteaRun(t, func(*testing.T, *url.URL) {
 		session := loginUser(t, "user1")
-		token := getTokenForLoggedInUser(t, session)
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeSudo)
 
 		org := api.CreateOrgOption{
 			UserName:    "user2_org",