Draft: Allow special surfaces to receive all keyboard input

Certain technologies that we mean to support, namely X11, are designed with the premise that clients can eavesdrop the users' input. If we want to fully support them, we need to offer such information so apps keep working.

This specifically will allow us to support, among others, Push-to-Talk implementations that like electron's iohook that just expect to filter all user input themselves instead of actively requesting what they need.

Draft because kwin's counter-part still needs work