AVRCP: Test MediaBrowsers before trying to use

MediaBrowserService can reject the connection from a MediaBrowser.

Test packages beforehand so we don't advertise browsing for a player we
can't browse to.

Refactor and cleanup some code around building media player lists and
remove some dead code.

Bug: 33390650
Bug: 32382082
Test: use carkit to browse to different players
Change-Id: I5a4c18ab77a24f3cf2aa34d1c15e3213edfed61d