[Postmortem 4.1] Make mlperf.conf static in loadgen, enable automatic Pypi release

[arjunsuresh]

This PR does the below changes:

Make loadgen automatically load the mlperf.conf file.

1. mlperf.conf file is now distributed along with the loadgen source and is moved to the loadgen folder. There is a soft link at the repo root so that old workflows won't break. For this a MANIFEST.in file is added.
2. Reference implementations are modified to remove the --mlperf_conf option.
3. Restrict the keys that can be provided in the user.conf file.

Fix compilation warnings in loadgen

1. Compilation warnings for loadgen except -Wunused-parameter are fixed.
2. Github test for loadgen is modified to fail on any change which introduces a compilation warning.
3. All the modified files are formatted to get the github action to pass.

Enabled Automatic pypi upload for loadgen wheels

1. pip install mlcommons_loadgen can now be used to install loadgen on Linux, macOS and Windows
2. A VERSION.txt file is added for loadgen for version info with an option for patch version
3. The VERSION.txt file is automatically updated (only the patch version being updated) and new wheels released whenever there is a change inside the loadgen directory.
4. https://pypi.org/manage/project/mlcommons-loadgen/releases/

Action item for the submitters

1. Stop passing the mlperf.conf file to the loadgen - if this is done, mlperf_log_detail will have an error and the submission checker will fail.
2. For python applications, pip install mlcommons_loadgen can be used

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