Add a model loading/unloading stress test

To ensure stability of NNAPI, for every model, this test continuously loads
the model for 30 minutes without doing any inference.

Bug: 123042197
Test: build_and_run_benchmark.sh model-loading-stress
Change-Id: I6b8522b627092e7cafb8370037aa5d66d71f76aa
4 files changed