Implement NNAPI compilation caching runtime.

Implement compilation caching in runtime and add compilation caching
tests.

The token from user is transformed during the partitioning process by
SHA256 hasher based on
- device name
- device version string
- execution preference
- which operation (index) is included in the partition

Add tests to test compilation caching and the partitioner.

Bug: 119616526
Test: NeuralNetworksTest_static
Change-Id: I41e9dce10d95f744382894299c0d68bb8d10c08c