Fix some issues with audiopolicy_tests

1. Update AudioPolicyManagerTestClientForHdmi to allow adding
   multiple supported formats.
2. Add missing assertions for helper functions to complete with
   no failures.
3. Set the name of the loaded config file so it can be seen
   in the APM config dump printed to syslog.

Bug: 201089251
Test: atest audiopolicy_tests
Change-Id: I02dac749b7927ee6f048156d0f8aa16af09a50ea