Add new Hearing Aids commands to improve L/R Sync

Prototyping new commands to the Hearing Aids devices to improve the
Left/Right Sync issues. The new commands are:
1. Add a new byte parameter to the START command that indicates the
other side device is actively streaming or disconnected,
2. Whenever there is an LE Connection Update event from the phone BT
controller, send a new Status Update command to all connected devices,
3. Whenever one side gets disconnected or starts streaming, send a new
Status Update command to the other side to inform about this change.

Bug: 117778955
Bug: 120921220
Test: Manual Testing with Hearing Aids
Change-Id: I5c94867d4574802025e3b433573e52d3c40c9828