Add decoder APIs and unit tests in tile-coding experiment

In the tile-coding experiment,
1. In tile decoder, added 2 set control APIs:
   VP10_SET_DECODE_TILE_ROW and VP10_SET_DECODE_TILE_COL. It allowed
   users to set the range of decoding at frame level.
2. Added a unit test while tile-coding experiment is on. It tested
   both tile encoder and decoder to make sure the encoded frame
   can be decoded as a whole frame or as independent tiles.

Change-Id: I73fd0632b685047cb9376008127cde72efa3fb2b