Add customizable user roles (#18641)

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

spec/controllers/admin/statuses_controller_spec.rb

@@ -3,7 +3,7 @@ require 'rails_helper'
 describe Admin::StatusesController do
   render_views
 
-  let(:user) { Fabricate(:user, admin: true) }
+  let(:user) { Fabricate(:user, role: UserRole.find_by(name: 'Admin')) }
   let(:account) { Fabricate(:account) }
   let!(:status) { Fabricate(:status, account: account) }
   let(:media_attached_status) { Fabricate(:status, account: account, sensitive: !sensitive) }