Control audio HAL services in start/stop

Some system services (e.g. SoundTriggerMiddleware) assume that
whenever they start, the audio HAL is in its default (reset) state.
init.rc scripts tie the lifetimes of the audio HAL and system
processes, but when using stop/start this is not the case, and this
may cause spurious crashes in this case.

stop/start is apparently being relied on in some test infrastructure,
so this change is needed to avoid causing problems for those systems
or false detection of problems, which are not actually present in
production.

Bug: 154029444
Test: Manually verify that the audio HAL is stopped on
      'adb shell stop', restarted on 'adb shell start' and that the
      system boots correctly after.
Change-Id: Icb6eeddfa48b1a49a4d48baae41f9086eb83a9ca

media/audioserver/audioserver.rc

@@ -14,6 +14,20 @@ on property:vts.native_server.on=1
 on property:vts.native_server.on=0
     start audioserver
 
+on property:init.svc.audioserver=stopped
+    stop vendor.audio-hal
+    stop vendor.audio-hal-4-0-msd
+    # Keep the original service names for backward compatibility
+    stop vendor.audio-hal-2-0
+    stop audio-hal-2-0
+
+on property:init.svc.audioserver=running
+    start vendor.audio-hal
+    start vendor.audio-hal-4-0-msd
+    # Keep the original service names for backward compatibility
+    start vendor.audio-hal-2-0
+    start audio-hal-2-0
+
 on property:sys.audio.restart.hal=1
     restart vendor.audio-hal
     restart vendor.audio-hal-4-0-msd