[Pytorch NNAPI] Add compilation_preference & relax_f32_to_f16 APIs (#78758)
Summary:
compilation_preference is one of:
ANEURALNETWORKS_PREFER_LOW_POWER = 0
ANEURALNETWORKS_PREFER_FAST_SINGLE_ANSWER = 1
ANEURALNETWORKS_PREFER_SUSTAINED_SPEED = 2
relax_f32_to_f16 calls Model_relaxComputationFloat32toFloat16
Test Plan:
Tested on device with nnapi models
* Works with existing exported models
* Works with new exported models with options
Differential Revision: D36433236
Pull Request resolved: https://github.com/pytorch/pytorch/pull/78758
Approved by: https://github.com/kimishpatel
