Give a better error message for blocked users trying to edit

If a user is blocked, there is no notice for that, only a "the edit can not be
saved" is the error message when he try to edit. With this change, the user
gets a proper error message (You have been blocked from editing)

Bug: T78315
Change-Id: Idbe078452e50d73fc44ba4a89f082c1a5f4b4a38
Merge "Give a better error message for blocked users trying to edit"