text-input-v3 issues

[Drakulix]

Reported here

This is because Smithay, the base component of cosmic-comp, doesn't strictly follow the protocol.

The cursor position set by clients with text_input_v3::set_cursor_rectangle requests should be double-buffered and applied with text_input_v3::commit requests, but Smithay seems to apply it immediately on text_input_v3::set_cursor_rectangle requests. Also, the protocol says the pending cursor position should be cleared on text_input_v3::commit requests, but smithay remembers the old cursor position.