Improve "generate new access token" form (#33730)

Fix: https://github.com/go-gitea/gitea/issues/33519

As discussed in [PR
#33614](https://github.com/go-gitea/gitea/pull/33614), the
ScopedAccessTokenSelector Vue component is not particularly useful.

This PR removes the component and reverts to using HTML templates. It
also introduces some (hopefully) useful refactoring.

The Vue component was causing the UX bug reported in the linked issue.
Required form fields are now properly working, as expected (see
screenshot).

![Screenshot from 2025-02-25
22-00-28](https://github.com/user-attachments/assets/41167854-0718-48b0-a3ee-75ca3a7b8b20)

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

options/locale/locale_en-US.ini

@@ -917,7 +917,6 @@ delete_token_success = The token has been deleted. Applications using it no long
 repo_and_org_access = Repository and Organization Access
 permissions_public_only = Public only
 permissions_access_all = All (public, private, and limited)
-select_permissions = Select permissions
 permission_not_set = Not set
 permission_no_access = No Access
 permission_read = Read