Support quantized models and examples in tests

- Revised test_generator
- Added a quantized example (average pool) to
  the regression test suite
- Added generated test to NeuralNetworksTest
- Revised test harness

Bug: 63905942
Test: tools/test_generator/test.py
Test: /data/nativetest64/NeuralNetworksTest/NeuralNetworksTest on Angler
Change-Id: I8d0ae3031db5d54ac9f46c7b4d916d0560265730
14 files changed
tree: d7655a001b1018d730cafab9080bd0e94a02e68c
  1. nn/
  2. Android.bp