[feature] Support pipx run with different name in entry point natively if a package wants to support it

How would this feature be useful?

Currently, running pipx run build does not work; it requires pipx run --spec build pyproject-build. It would not be safe to add a build script entry point to pypa/build, due to how common that name would be. It would be nice to have a way for a package to tell pipx run “here’s my entry point, use this”. I know the author of pypa/build (@FFY00) was interested in supporting pipx (and pipx run build would be fantastic, imo). This affects projects with a common or unsafe name for an entry point.

Describe the solution you’d like These are some initial ideas:

1. If a matching console entry point is not found, pipx run could fall back on python -m <name> if <name>/__main__.py is present.
2. There could be a pipx entry point in a package. Say "pipx.run.<name>". If this was specified, then that would be used by run. (I’m not very familiar with non-console entry points, but I think this is a valid way to use them)
3. Have a dict in pipx for common packages. (probably not a good idea? If #596 went through, then one could argue that build, also being in the PyPA, would be a valid candidate for special treatment. This doesn’t solve the issue generally, though)

These ideas would allow a package that supports pipx to have a dependency that supports pipx and not trip up the discovery.

Describe alternatives you’ve considered

This potentially would be a useful alternative to https://github.com/pipxproject/pipx/issues/177. I really like the idea of pipx run -m, as it would let me do things like pipx run -m rich, since rich so far has resisted adding an entry point and is python -m rich.<stuff> only.

[henryiii]

This was completed in #615 and released in 0.16, and is now even available on all the GitHub Actions runners! 😃

[uranusjr]

Makes sense. I may find some time to implement this and see how it works in practice.