HAL interface for compilation and execution hints

The following AIDL types are added:
 - TokenValuePair
 - PrepareModelConfig
 - ExecutionConfig

The following AIDL methods are added:
 - IDevice::prepareModelWithConfig
 - IPreparedModel::executeSynchronouslyWithConfig
 - IPreparedModel::executeFencedWithConfig
 - IBurst::executeSynchronouslyWithConfig

The compilation and execution hints are being stored as a list of
token-value pairs as part of the PrepareModelConfig / ExecutionConfig.
And the PrepareModelConfig / ExecutionConfig parcelables are created in
order to make future extensions to the execution related interfaces
easier.

It is the drivers responsibility to verify the hints, and it is allowed
for the driver to ignore them.

Bug: 203248587
Test: neuralnetworks_utils_hal_aidl_test
Change-Id: I98240fd75089fc85cdfcaa0be28aab8a6f0dfca5
Merged-In: I98240fd75089fc85cdfcaa0be28aab8a6f0dfca5
(cherry picked from commit 0e671f3e)