Add customizable user roles (#18641)

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

app/policies/invite_policy.rb

@@ -2,19 +2,19 @@
 
 class InvitePolicy < ApplicationPolicy
   def index?
-    staff?
+    role.can?(:manage_invites)
   end
 
   def create?
-    min_required_role?
+    role.can?(:invite_users)
   end
 
   def deactivate_all?
-    admin?
+    role.can?(:manage_invites)
   end
 
   def destroy?
-    owner? || (Setting.min_invite_role == 'admin' ? admin? : staff?)
+    owner? || role.can?(:manage_invites)
   end
 
   private
@@ -22,8 +22,4 @@ class InvitePolicy < ApplicationPolicy
   def owner?
     record.user_id == current_user&.id
   end
-
-  def min_required_role?
-    current_user&.role?(Setting.min_invite_role)
-  end
 end