Draft: kcms/tablet: Improve the look of output mapping

Very very WIP, do not expect this to work correctly.

This is laying the groundwork for a future feature allowing the map a portion of the tablet area as well. But this should also cut down on the confusion of what the existing feature does, which we've received some complaints over. Note that this will look out of place until the UI overhaul is merged, since it will cut down on the noise and I put it in a better spot :)