AudioFlinger: defer restartIfDisabled()

Defer restartIfDisabled() to the end of
the threadLoop worker thread, allowing execution
without any mutexes held. This prevents mutex
order issues.

To accomplish this, we add a DeferredExecutor object
to ThreadBase, which allows adding functors and dtors
to execute at the end of the worker loop,
where no mutexes are held.

Test: atest AudioPlaybackCaptureTest
Bug: 345400492
Bug: 345676143
Change-Id: I1d7f491fc1289882ce67cb7289b3bc1b58e81d23