Android VideoSource: Add adaptOutputFormat function

The Java VideoSource class wraps the C++ AndroidVideoTrackSource.
AndroidVideoTrackSource is the object actually owning the VideoAdapter.
We currently control the VideoAdapter through the Java VideoCapturer,
but it is more natural and direct to control it through the Java
VideoSource class. This CL adds the necessary function to do this, and
the function in VideoCapturer is deprecated.

BUG=webrtc:6391
R=sakal@webrtc.org

Review URL: https://codereview.webrtc.org/2350933006 .

Cr-Commit-Position: refs/heads/master@{#14332}