Implement visitation of type aliases and parameters (#5927)
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Part of #5062
Requires https://github.com/astral-sh/RustPython-Parser/pull/32
Adds visitation of type alias statements and type parameters in class
and function definitions.
Duplicates tests for `PreorderVisitor` into `Visitor` with new
snapshots. Testing required node implementations for the `TypeParam`
enum, which is a chunk of the diff and the reason we need `Ranged`
implementations in
https://github.com/astral-sh/RustPython-Parser/pull/32.
## Test Plan
<!-- How was it tested? -->
Adds unit tests with snapshots.
