Re-implement the queue, now leveraging a bottom sheet too.
This makes the queue much easier to open, and actually plays along with
the new transition system. I really hope this doesn't have a stupid
gotcha that ruins the UX. Please. Please. Please.
Use BottomSheetBehavior with the playback sheet.
This is the result of two weeks of painful hacking to get a working
implementation that did not immediately have a brain aneursym. It
also requires me to still vendor BottomSheetBehavior for the time
being. However, this greatly reduces technical issues on my end and
allows the addition of new playback UI concepts, while still
retaining the UI fluidity of prior.
