Merge changes from topics "syncexec-ndk-shallow-aosp", "replace_asymm", "fp16-op-add"

* changes:
  Implement ANeuralNetworksExecution_compute() and add related properties.
  Adds float16 support for CONCATENATION.
  Add float16 support for SPLIT
  Fix TRANSPOSE op.
  Adds float16 support for LOGISTIC/SOFTMAX.
  Adds float16 support for RELU*.
  Adds float16 support for MUL/DIV.
  Add float16 support for TOPK_V2 op
  Replace TENSOR_QUANT16_ASYMM with TENSOR_QUANT16_SYMM
  Refactor HAL version validation
  Adds float16 support for ADD operation.
  Implement implicit float16 conversion in test generator.
  Add Float16 support to SUB
  Add layer normalization support to LSTM op
  Add Float16 support to TANH
  Add Float16 support to MAXIMUM and MINIMUM
  Add Float16 support to GATHER
  Add Float16 support to CAST
  Add Float16 support to TILE
  Fix generated test names for Float16 variations
  Fix TENSOR_FLOAT16 support in CTS generator
  Replace NN_CHECK with more flexible NN_RET_CHECK
  Add synchronous execution API ANeuralNetworksExecution_compute().
  Adds float16 support to generated tests.
  Autogenerates VTS ValidationTest tests.