Draft: kcms/tablet: Begin to use libwacom, use actual number of stylus buttons
libwacom has tons of useful information we can use. In this case, we can use it to report the actual number of stylus buttons available and not always 3.
Implementors Note
- Database implementation is stuck inside of the model, since that's the only place it's used. Making it accessible everywhere in the KCM should be the eventual goal, but for this MR I'd like not to get caught up in refactoring.
- libwacom is used in the old wacomtablet KCM, and should be generally available everywhere.
Edited by Joshua Goins