[roll] Roll fuchsia [aml-securemem] Adopt isolated state

Adopting the isolated state async patterns described in
I25561c689ff86c477bd5dc78290e0d0557bb757c. This gets rid of a lot of
thread checking and jumping code.

The threading model remains broadly unchanged but the points of thread
hopping have been shifted to object boundaries:

Prior to the CL:
- AmlogicSecureMemDevice gets called from both the DDK dispatcher and
  the SysmemSecureMemServer's async::Loop. It then uses a ClosureQueue
  to hop to the right dispatcher (DDK dispatcher).
- SysmemSecureMemServer also gets called from both the DDK dispatcher
  and its own async::Loop. It also uses a ClosureQueue to hop to the
  right dispatcher (async::Loop dispatcher).

After the CL:
- AmlogicSecureMemDevice is only used from the DDK dispatcher.
- SysmemSecureMemServer is only used from an async::Loop dispatcher,
  which the AmlogicSecureMemDevice device owns.
- Communication between these objects happen via DispatcherBound and
  async_patterns::Receiver.
- SysmemSecureMemServer stops the FIDL connection on destruction.

Each object is used from their associated dispatcher, the thread
hopping is encapsulated by the async_patterns library. So all the
ClosureQueue usages are removed.

Tried to simplify/rewrite comments that no longer apply.

Test: ran the `core.sherlock-release` bot. played some DRM-ed video on
hardware.

Cq-Include-Trybots: luci.turquoise.global.try:run-postsubmit-tryjobs

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/818968
Original-Revision: 66044694e2cf7226e2dfc363515b37c6b370d62d
GitOrigin-RevId: 97c0a7cebb95dbf42a5ca3de5b802c7bba789e74
Change-Id: I43dea34c0f771a76711ad18fa97f5db6887cb616