av1: Allow odd width/height for YUV420

Allow odd width/height values for the gav1 software decoder.

Notes:
* We already allocate the graphic block with a stride that is a
  multiple of 16, that behavior is retained.
* We also allocate the graphic buffer with a height alignment of 2 (this
  change is needed because fetchGraphicBlock fails for odd height
  values.
* We set the correct "crop" value in createGraphicBuffer() which will
  handle odd width/height appropriately.
* This change also enables decoding of AVIF images that have odd
  dimensions.

This CL contains changes to the mainline files.

Test: CtsMediaTestCases still pass
Bug: 175243729

Change-Id: I6b811fed5cc9c599177fffd24d4d96d65c52ae8e