AVRCP: Prevent NPEs with browsing-only players

When a player doesn't have an active controller, the MediaPlayerInfo
is identified by package name instead.

Add the list of media players to the dumpsys.

Test: connect with browsing player that has no active session
i.e. GPM right after reboot with no paired devices
Bug: 37197672
Change-Id: I064b1dcce33172ceb7bcad2af4b214ea4fc4198c