Floss: Implement Pandora L2CAP profile

Bug: 300954032
Bug: 300942862
Bug: 300942863
Bug: 301000121
Bug: 301000122
Test: mma packages/modules/Bluetooth && pts-bot L2CAP
Tag: #floss
Flag: EXEMPT floss only changes
Change-Id: If3ac5043ec9894c3d6ae9773e07d2e52513665ba