text-input: Don't reject enable requests when unfocused
Created by: dcz-purism
The prevoius implementation would always raise an error in the following sequence:
- → enter
- → leave
- ← enable
The text-input type is not equipped to manage the validity of clents' requests, which should be handled in the compositor, as rootston does.
There is one scenario where this error should stay; namely immediately after creating the text input, but handling it introduces additional state and complexity, so I decided against it.
This should also make terminals work again, fixing https://gitlab.gnome.org/GNOME/gtk/merge_requests/369 from the other side.