NNAPI VTS: Add validation for Priority

This CL also cleans up the validation framework code.

Bug: 67828197
Test: mma
Test: VtsHalNeuralnetworksV1_*TargetTest
Change-Id: I84661fb2b8204148788d10425ca0ac986158b15f
Merged-In: I84661fb2b8204148788d10425ca0ac986158b15f
(cherry picked from commit da1a69288054dcbe9e91943d408a65b3c59c4a09)
10 files changed