Add option for turning off click's standalone_mode

[ferenc-rad]

Add a new commad line option that enables turning off click's standalone_mode, thus allowing collecting memory traces with viztracer:
https://click.palletsprojects.com/en/stable/api/#click.Command.main
https://viztracer.readthedocs.io/en/latest/

Checklist

• I have added tests that prove my fix is effective or that my feature works (discussed: no need for tests for this developer feature)
• New and existing unit tests pass locally with my changes
• I have made corresponding changes to the documentation

[yousefmoazzam]

I had a go at seeing if this could be done through click; alas, I think you're right that this has to be done outside of click.

I tried to sneakily give the main() function a bool parameter called standalone_mode and then define a@click.option on it. The flag works and is available on python -m httomo rather than on python -m httomo run, but it doesn't change the behaviour - I think this was simply defining a flag that happened to have the same name, but didn't actually hook into click's standalone_mode parameter.

On the note about tests, given that this is essentially a secret flag for developers only, and that adding a test would probably require some fiddling with __main__.py, I think I'm content to say that as long as we know that all other CLI tests pass, then that's good enough.

The IRIS CI is in a bit of a weird state due to scheduled maintenance occurring over the weekend, but I can confirm that the tests pass locally, and running pipelines without this flag seems unaffected.

Please feel free to update the branch as needed, and then I think this is fine to merge, thanks! 🙂