local playback silent after interruption (e.g. by phonecall)

[grobian]

When playback gets paused by e.g. an incoming phonecall, the output is silent after resuming. The playback must be stopped and resumed in order to get sound again.

[Difegue]

I can't fully test this since my test SE doesn't have a SIM in it, but I took some inspiration from Baseflow/XamarinMediaManager#615 and tried to write in a fix.
It works for me when interrupting the app with other media players, at least...

lmk how it goes, I might get on to #97 in a future update if this works.