Draft: Mark button events caused by tapping as such
This theoretically allows a caller to distinguish between a physical button click and a tap, allowing for different interaction methods based on the physcial interaction.
Closes #916
cc @zouxiaoyi
Very much a draft, it's missing test cases and I'm really questioning the use-case for this - in part because this requires a wayland protocol to be useful to clients (instead of just the compositors)