Fix package_name resolution when module differs from distribution name

[kdeldycke]

There is an issue we glossed over when closing #2331: I analyzed the bug report as requiring a new slot/field to be added to the @version_option decorator. I promptly close the issue as we decided in #3527 to freeze @version_option.

But looking closely #2331 did not asked for a new module_name field. That was my suggestion on how to address the user request.

So reframing it, #2331 is a report that @version_option is producing a RuntimeError for users in some legitimate situations. This breaks the out-of-the-box experience of @version_option.

In fact, the limitation has been pointed out by @davidism a couple of years ago at #1884 (comment):

If someone figures out a way to get the distribution version from the entry point name with importlib.metadata, I'd welcome a PR to improve our detection, but from my experiments with it I was not able to find how to do it. For now, I'll update the changelog.

So this is a PR to implement that fix.

Addresses:

• version_option doesn't automatically detect version anymore with click 8.0.0 #1884
• version_option module name and package name are not equivalent #2331
• version_option ignores package_name #3125

[kdeldycke]

Just rebased this PR. It is ready to be merged to stable.