Merge changes from topics "replace_asymm", "fp16-op-add"

* changes:
  Replace TENSOR_QUANT16_ASYMM with TENSOR_QUANT16_SYMM
  Fix VTS ValidationTest for 1.2 ops.
  Adds float16 support to generated tests.
  Autogenerates VTS ValidationTest tests.
  Fix VTS ValidationTest for 1.2 ops.
  Separates VTS tests by HAL version.