media/stagefright: add support for codec attributes in MediaCodecInfo

- Move away from int flags, and signal capabilities in info AMessage/Map
instead.
- Add more attributes (other than isEncoder).
- Parse aliases, attributes and performance points from XML
- Add plumbing for codec aliases and attributes
- Use proper 'mediaType' phrase for supported types.

Bug: 119631295
Bug: 112370870
Bug: 112374531

Change-Id: I41ea555ca26ab09be176fb96a3138043d960caa3