[ty] use type context more aggressively to infer values when constructing a `TypedDict` (#20806)
## Summary
Based on @ibraheemdev's comment on #20792:
> I think we can also update our bidirectional inference code, [which
makes the same
assumption](https://github.com/astral-sh/ruff/blob/main/crates/ty_python_semantic/src/types/infer/builder.rs?rgh-link-date=2025-10-09T21%3A30%3A31Z#L5860).
This PR also adds more test cases for how `TypedDict` annotations affect
generic call inference.
## Test Plan
New tests in `typed_dict.md`