Add a circular indicator to playback icons.
Sometimes it can be too difficult to tell apart the active and inactive
states of the shuffle/loop icons. However, there is really no good way
to improve the contrast on these icons without some kind of muddled UX
fragmentation, or god-awful design. Try to settle on the okay-est
version, which is to use colorPrimary with a dot indicator on views we
control, and use a more muddled semi-transparent icon on views we don't
control, like notifications and widgets.
Change most of the external layout/drawable code to use
colorControlHighlight instead of selection_color so that control
over which kind of selection color is used is more fine-grained.
