AudioService: log metric for audio focus requests

Log grants and denials by appOps, per focus request type.

Bug: 316414750
Flag: android.media.audio.ro_foreground_audio_control
Test: go/tex-metric/media_audio.value_audio_focus_gain_appops_denial
Change-Id: I949e35ee3b79003778eede630eff4d26b1e63ebb