feat: script improvements

[henryiii]

This makes several improvements to the python -m dependency-groups script:

• Adds a dependency-groups script, so that uvx dependency-groups and pipx run dependency-groups works, along with pipx install/uv tool install.
• Adds a cli extra so that pipx run dependency-groups[cli] works on Python < 3.11
• Allows more than one extra to be requested
• Adds a --list to quickly see all the dependency groups available

I don't think there are CLI tests yet, so didn't add tests.

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📚 Documentation preview 📚: https://dependency-groups--13.org.readthedocs.build/en/13/

[sirosen]

Yep, this seems like a good enhancement to me! Originally I thought making python -m dependency_groups the way to run it would be sufficient, but you make a good point about pipx/uvx.

I'd already been considering maybe adding --list, so I'm onboard for that.

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This is reminding me that I need to rig up CLI tests. I've got some specific ideas on how I want that to work, so I'll get to it soon.

[sirosen]

Just curious, does explicitly raising a SystemExit behave significantly differently from sys.exit? (Will it capture the outer error in __cause__ by default?)

If I need to adjust my habits around this, it's a good opportunity to learn.

[henryiii]

It doesn't require an import, is microscopically faster, and is a bit more explicitly obvious as a control flow statement than a NoReturn function. If someone does explicitly catch it, like in tests, you can inspect the __cause__/__context__/__suppress_context__, as well, but it doesn't show the cause with the default exception hook.

See https://www.youtube.com/watch?v=ZbeSPc5wL0g.

Edit: ignore what I put here originally, exception suppression works as you'd expect if you inspect it, I just forgot how it worked for a minute.