Switch media fw hotword permission check to PermissionChecker (native)

PermissionChecker now includes some higher level logic for allowing the
HotwordDetectionService to access mic audio and hotword audio.

Bug: 190011174
Test: manual - sample app can read audio (with a few other wip changes)
Change-Id: I5e624933962ad07ebe4abbde8b884585a052e96b