Add customizable user roles (#18641)

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

app/views/admin/roles/index.html.haml

@@ -0,0 +1,17 @@
+- content_for :page_title do
+  = t('admin.roles.title')
+
+- content_for :heading_actions do
+  = link_to t('admin.roles.add_new'), new_admin_role_path, class: 'button' if can?(:create, :user_role)
+
+%p= t('admin.roles.description_html')
+
+%hr.spacer/
+
+.applications-list
+  = render partial: 'role', collection: @roles.select(&:everyone?)
+
+%hr.spacer/
+
+.applications-list
+  = render partial: 'role', collection: @roles.reject(&:everyone?)