Implement helper method to find module path of value

[Jake Howard]

Finding the module path for where a given class or function is defined is functionality used in a few places across the Django codebase. Whilst in the majority of cases, f"{val.__module__}.{val.__qualname__}" is enough, there are some cases it's not.

As part of #35859, a few more cases of this pattern are being added to the codebase. I think we're now at the ​point where it makes sense to extract this out to a helper function somewhere in django.utils. The implementation in django.migrations.serializer.TypeSerializer seems to be the most robust, however will want some more thorough testing based on different input types.

[Jake Howard]

Probably worth holding off on this ticket until #35859 is merged, so all uses can be covered.

[Natalia Bidart]

Thank you Jake for creating the ticket. Could please enumerate the locations of where this functionality is found?

[Jake Howard]

That sounds like the right approach to me - thanks for picking this up!

[Jacob Walls]

#35859 was merged.

[Vimal Sahani]

​https://github.com/django/django/pull/21875

[Vimal Sahani]

PR submitted: ​https://github.com/django/django/pull/21873

[Jacob Walls <jacobtylerwalls@…>]

In 0398417c:

Fixed #36523 -- Added django.utils.module_loading.qualname() helper.

Thanks Jake Howard for the reivew.