Add BrowsablePlayerConnecter to handle creating the browsable player list

BrowsablePlayerConnector connects to all provided browsable players and
checks if connection succeeds as well as the root folder has more than
zero items. The results are returned in a callback.

Bug: 68854188
Test: Compile
Change-Id: I32023836c3bfba496cd216ade246c7e217a99999