floss: avrcp: propagate media information through topshim

Propagate the parsed media information through the rust/c++ barrier.
Avoided using custom types and used all native cxx-supported ones.

Bug: 240780471
Tag: #floss
Test: ./build.py
BYPASS_LONG_LINES_REASON: Bluetooth likes 120 lines

Change-Id: Idd156aa3941870dcb69d5832acdfb0114ecf4979