AVRCP 1.6: media browsing support on Target(1/3)

-> As a part of Avrcp 1.6 upgrade, added support
   for following features:
   [1] setAddressedPlayer
   [2] setBrowsedPlayer
   [3] getFolderItems scope=VFS/NowPlaying/Search
   [4] changePath
   [5] getItemAttributes
   [6] playItem
   [7] getTotalNumberOfItems
   [8] search string in current browsed path.
   [9] AddToNowPlaying
-> Defined functions and enhanced structures to
   support above mentioned features.
-> Added Dual RC support.

Bug: 19361366
Merged-In: I45ed60e337b57c686d9693e19993fee1ce3c2504
Change-Id: I45ed60e337b57c686d9693e19993fee1ce3c2504