Get changes made in bevy_pancam fork merged upstream

[MeoMix]

I added really rough support for touch events as well as fixed some edge cases with clamping. I tried getting them merged in but wasn't able to sufficiently convince the author of the quality of my efforts. I didn't necessarily disagree, but it wasn't valuable to me to put more time into it at that point.

Still, it would be nice to not maintain a custom fork.