Improve the way the compact playback view transforms into the full
playback view by splitting their view animations in two. This makes
the transition more akin to the Android 12 notification menu, which
due to the nature of how I'm fading views really does make it more
user friendly. Also re-add the "Now Playing" title and a new subtitle
displaying the currently playing artist.
Completely refactor PlaybackBarLayout into PlaybackLayout, which now
not only handles the bar behavior but also allows for one to slide
up the bar layout into the full playback layout. This was largely
adapted from umano's AndroidSlidingUpPanel, albeit heavily minified
and mixed with the previous window inset tricks of the previous layout.
There are still some tweaks to be made, but this implementation seems
to be really good.
