feature: Support conventions to mark objects as public

[pawamoy]

Is your feature request related to a problem? Please describe.

In the ecosystem, we have common conventions to mark objects as public:

• redundant imports: import x as x
• redundant from-imports: from a import x as x
• wildcard imports: from a import *

Users rely on those, but Griffe currently does not support them. This affects both our API checker and mkdocstrings-python: some objects might be wrongly considered private instead of public, or the opposite.

Describe the solution you'd like

Support these conventions.

A few solution ideas:

• Use the public attribute? When visiting modules, set public = True on objects imported like that. Later, if we find __all__ is defined, set them back to None. Not sure I like using public like that, internally.
• Write extensions. I think this would require adding a hook like on_alias? Extensions do not run during wildcard expansion though.
• Add metadata to objects? This metadata ²would then be used by the "public" logic?

Describe alternatives you've considered

/

Additional context

See mkdocstrings/python#39.

[pawamoy]

Since we don't recommend relying on these conventions in our docs, we should probably implement this as (insiders) extensions. For this we'll probably need new hooks:

• on_alias: we could name it on_import, but during inspection we're not sure it's actually an import. Since we create an Alias, that follows the existing naming pattern (on module, on function, etc.).
• on_wildcard_expansion? or maybe we can combine it in on_alias by passing relevant info?

[pawamoy]

Now available as https://mkdocstrings.github.io/griffe-public-wildcard-imports/ and https://mkdocstrings.github.io/griffe-public-redundant-aliases/ Insiders extensions!