codec2: Add support for sync frames in hevc encoder plugin

Bug: 135515629
Test: set forceGoogleEncoder to true in VideoCodecTestBase.java
Test: atest android.media.cts.VideoCodecTes.testSyncFrameHEVCCBR

Change-Id: I869506d13d695b90a280d9bcd42c307043269b74
2 files changed