avrcp: PTS mode track selected

PTSTesting mode forces "browsing not supported" case when handling TRACK_CHANGE
notification command.

Respond with UID 0 when track is selected (both INTERIM and CHANGED responses);
resposond with UID (long)-1 in INTERIM when no track is selected.

Bug: 199827901
Test: gd/cert/run
Tag: #stability
Change-Id: I4a443897fc5236fcf57c8101ffc0458df95e43f4
(cherry picked from commit 1d19d1db74f40ce797cd98683f2300784f1c6a8f)