Merge "VTS: add support for sending empty first frame in EncodeTest" into rvc-dev am: fc8cd670b7 am: d5ef9acf95 am: dba8a45683 am: 7a76363f64 am: dd23f6d680

Change-Id: I54966eaa0f1ed77e1d3d4de6e1085f7ab19da9cd