Draft: inputmethod: Send pre-defined commit message to client on user interaction
In some IM backends pre-edit text should be submitted on user interaction, in some it should be discarded. This used to be a flag sent to the client along with the commit string ahead of time.
TextInputV3 does not have a flag for this, so we handle it compositor side.
It's a draft state for some testing.
My testing:
- modified some code in my input method playground to have a different preedit and commit string
- tested in gedit as Qt apps deliberately prefer TextInputV2 as it's more powerful
It needs someone who meaningfully uses an IME with this to confirm it works well IRL. @xuetianweng