Use Model instead of Self in parms and add AltersData inheritance

[emmanuel-ferdman]

PR Summary

refresh_from_db, arefresh_from_db, _do_update, _get_pk_val, and unique_error_message used Self in their parameter types, which is unsound in contravariant positions - overriding these methods in a subclass with the same Self pattern triggers reportIncompatibleMethodOverride in pyright/ty/pyrefly because QuerySet[Model] is not assignable to QuerySet[MyModel] (LSP violation). This PR changes these to use Model instead, which is the widest valid type and what the runtime actually accepts. Also this PR adds the missing AltersData to Model and QuerySet base classes to match the runtime MRO.

Fixes #2605.

[sobolevn]

Let's please add a assert_type test for this, it should be possible to override Model.refresh_from_db method with the correct annotation.

[emmanuel-ferdman]

@sobolevn had it ready in my local tests :)

[sobolevn]

MyModel won't work here, right?

[emmanuel-ferdman]

Right, QuerySet[MyModel] errors on both mypy and pyright since it narrows the parameter type. Should we add another test case for it?

[sobolevn]

Yes, please. But, it seems kinda right to have it typed as QuerySet[MyModel]?

Because passing from_queryset=QuerySet[SomeOther] with no error does seem like a false negative to me.

Do you have any ideas on how we can make this right?

[emmanuel-ferdman]

We could try self: _Self with QuerySet[_Self] - this ties the queryset to the actual model type. So user.refresh_from_db(from_queryset=article_qs) would correctly error. It's stricter than runtime since QuerySet[Model] gets rejected for typed subclass instances, but I think passing a wrong model's queryset is a bug waiting to happen anyway :)