Improve feedback messages incase menuitem is locked by one user

1.Currently, if a menu is being edited by "admin" user.
2.editor user tries to edit the menu item in menu editor then a generic error is shown "Failed to save menu item" which is not sufficient.

Expected:1A)Better to shown menu is locked by "admin" user.
1B)Or simply show lock for editor user on "edit menu" icon
2.Also show menu item parameters as read-only in menu editor.