Prevent deadlock when calling BT or Audio

Both Bluetooth and Audio APIs may require binder threads
to complete. As a result we must not block any binder threads
on calls to those APIs.

This method also adds TODOs for the changes that require changes
to the thread on which certain operations run.

Bug: b/329929065
Test: atest CtsMediaHostTestCases CtsMediaBetterTogetherTestCases AudioManagerRouteControllerTest
Test: Also manual using wired and bluetooth outputs.
Change-Id: Ided514035d657214233fa9a427949977a9ea35d5