Determine framework automatically before ONNX export (#18615)
* Automatic detection for framework to use when exporting to ONNX
* Log message change
* Incorporating PR comments, adding unit test
* Adding tf for pip install for run_tests_onnxruntime CI
* Restoring past changes to circleci yaml and test_onnx_v2.py, tests moved to tests/onnx/test_features.py
* Fixup
* Adding test to fetcher
* Updating circleci config to log more
* Changing test class name
* Comment typo fix in tests/onnx/test_features.py
Co-authored-by: lewtun <lewis.c.tunstall@gmail.com>
* Moving torch_str/tf_str to self.framework_pt/tf
* Remove -rA flag in circleci config
Co-authored-by: lewtun <lewis.c.tunstall@gmail.com>