Add first class support in PythonArtifact for Extension and ext_modules

[Eric-Arellano]

In https://github.com/pantsbuild/pants/pull/7235/files#diff-3ce39309d74098493a1f3c8107292a8d, we realized we have to add ext_modules to the Pants PythonArtifact so that its ABI gets properly resolved.

However, we are doing this using the deprecated tuple syntax, rather than using the expected Extension interface. See https://docs.python.org/3/distutils/setupscript.html#describing-extension-modules for what this should look like.

--

To land this fix, we will need to add first class support in python_artifact.py for Extension and ext_modules.

cc @jsirois

[sureshjoshi]

@Eric-Arellano Is this still an issue? I'm testing out adding 'mypyc' support and the easiest way is an extension module in setup.py of the python_distribution.

[Eric-Arellano]

Yeah, we still do this:

pants/src/python/pants/BUILD

Lines 24 to 29 in 331352e

	# NB: by setting `ext_modules`, we signal to setup_py and bdist_wheel that this library
	# has native code. As a consequence, bdist_wheel pins the ABI (application binary interface)
	# used when creating the wheel, which is a good thing. We should be setting this ABI to ensure
	# consumers of pantsbuild.pants are using a compatible interpreter.
	# TODO(7344): the tuple syntax for ext_modules is deprecated. Use Extension once we support it.
	ext_modules=[("native_engine", {"sources": ["pants/dummy.c"]})],