Run C++ tests on CI with run_test.py (#99956)
After https://github.com/pytorch/pytorch/pull/99559, we can now run C++ test with `run_test.py`. Although advance features such as `--import-slow-tests` and `--import-disabled-tests` won't work for now, there will still be a gain in reliability and performance as C++ can now be retried and run in parallel.
This covers all C++ tests in the CI including aten, libtorch, and Vulkan C++ tests across all platforms Linux, Windows, MacOS.
Notes:
* To support C++ test discovery, the env variable `CPP_TESTS_DIR` can be set to where the C++ test binaries is located
* Support pytest -k argument via run_test as this is used by pytest-cpp to replace `--gtest-filter`
* The XML output is in pytest format, but it's ok now because we don't have slow test or flaky test support for C++ test yet
* ~~I need to figure out why conftest.py doesn't work when I invoke pytest directly for C++ test, so `--sc` is not available for C++ tests at the moment. Proper pytest plugin like stepwise works fine though. I'll investigate and fix it in a separate PR~~ Found the cause, `conftest.py` is per directory and needs to be in any arbitrary directory that holds C++ test
* Two tests `test_api` and `test_tensorexpr` timed out on ASAN, I suspect that ASAN is now used on top of the python executable, which is slower than running native C++ code. IMO, it's ok to run these tests as before on ASAN for now
Pull Request resolved: https://github.com/pytorch/pytorch/pull/99956
Approved by: https://github.com/clee2000, https://github.com/ZainRizvi
