PLT-6763 Implement user access tokens and new roles (server-side) (#6972)

* Implement user access tokens and new roles

* Update config.json

* Add public post permission to apiv3

* Remove old comment

* Fix model unit test

* Updates to store per feedback

* Updates per feedback from CS

app/user.go

@@ -1224,6 +1224,10 @@ func PermanentDeleteUser(user *model.User) *model.AppError {
 		return result.Err
 	}
 
+	if result := <-Srv.Store.UserAccessToken().DeleteAllForUser(user.Id); result.Err != nil {
+		return result.Err
+	}
+
 	if result := <-Srv.Store.OAuth().PermanentDeleteAuthDataByUser(user.Id); result.Err != nil {
 		return result.Err
 	}