MediaCodecInfo.java: Added isFeatureSupported method to CodecCapabilities

Added isFeatureSupported method to CodecCapabilities, so that applications
can query whether codecs support various features.  For now
added one video-decoder feature:

FEATURE_AdaptivePlayback

Media playback applications can query it to see if the codec
supports seamless resolution changes during decoding.

Change-Id: I56b2cf1429f39f9b9e0243a990c95e7a64dd7ff7
Signed-off-by: Lajos Molnar <lajos@google.com>
Related-to-bug: 7093648