VolRef: add flags and permission tests

Increase the coverage of the volume APIs by adding new tests that check
the abs volume and ringer mode flags as well as AppOps and permission
checks

Removed the check timeouts since looper dispatchAll is waiting on the
result of all the handlers.

Improve robustness of tests. Dropped tests that rely on
MediaSessionManager since it is hard to mock the behaviour.

Test: build with EMMA_INSTRUMENT=true EMMA_INSTRUMENT_FRAMEWORK=true SKIP_BOOT_JARS_CHECK=true WITH_DEXPREOPT=false, atest VolumeHelperTest --experimental-coverage
Bug: 323273677
Change-Id: I5b812ccfd000afa5ddce10c1e3a1b9601b877ef2