Incomplete packages_distributions

[FFY00]

The search logic is very limited. I understand that we probably just wanted to keep things simple when it was added, but I want to understand if there's any plan to improve it?

importlib_metadata/importlib_metadata/__init__.py

Lines 899 to 904 in d66e35a

	def _top_level_inferred(dist):
	return {
	f.parts[0] if len(f.parts) > 1 else f.with_suffix('').name
	for f in always_iterable(dist.files)
	if f.suffix == ".py"
	}

In meson-python, I had to implement a more complete version of this logic. Would it make sense to port it here?

https://github.com/mesonbuild/meson-python/blob/61bb2b3315f4e312558778022ca6e87ffaed2700/mesonpy/__init__.py#L336-L359

[FFY00]

The current logic only returns pure Python top-level modules or package modules with at least one .py file.