FIX: Mark invited admins as 'approved' (#7459)

This prevents invited admins appearing as no-op reviewables in the queue when invite_only or require_approval is enabled.

app/controllers/admin/users_controller.rb

@@ -503,6 +503,7 @@ class Admin::UsersController < Admin::AdminController
     end
 
     user.active = true
+    user.approved = true
     user.save!
     user.grant_admin!
     user.change_trust_level!(4)