VT: Videocall datausage feature implementation.

[Problem] no interface defined to let application know
  how much data(bytes) used for video call.
[Cause] not implemented yet.
[Solution] defined a getter function to get how much bytes
  used for this video stream.

- MediaRecorder: app can query accumulative rtp data usage
    by a new API named getRtpDataUsage(uint64_t *bytes).
- MediaPlayer: app can receive final rtp statistics report when
    the stream closed by RTCP:BYE. app should accumulate bitrate
    when it received every rtp statistics reports.

Bug: 171688417

Change-Id: I426dc1f7dc384e1ec8958c2e96f060551fb39c5d
Signed-off-by: Diaesh Antony <diaesh.a@samsung.com>
Signed-off-by: Byeongjo Park <bjo.park@samsung.com>