Add customizable user roles (#18641)

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

app/serializers/rest/credential_account_serializer.rb

@@ -3,6 +3,8 @@
 class REST::CredentialAccountSerializer < REST::AccountSerializer
   attributes :source
 
+  has_one :role, serializer: REST::RoleSerializer
+
   def source
     user = object.user
 
@@ -15,4 +17,8 @@ class REST::CredentialAccountSerializer < REST::AccountSerializer
       follow_requests_count: FollowRequest.where(target_account: object).limit(40).count,
     }
   end
+
+  def role
+    object.user_role
+  end
 end