Evaluate default parameter value in enclosing scope

[dhruvmanila]

Summary

This PR fixes a bug in the semantic model where it would evaluate the default parameter value in the type parameter scope. For example,

def foo[T1: int](a = T1):
    pass

Here, the T1 in a = T1 is undefined but Ruff doesn't flag it (https://play.ruff.rs/ba2f7c2f-4da6-417e-aa2a-104aa63e6d5e).

The fix here is to evaluate the default parameter value in the enclosing scope instead.

Test Plan

Add a test case which includes the above code under F821 (undefined-name) and validate the snapshot.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[AlexWaygood]

Nice catch, LGTM!