[red-knot] Remove `Type::None` (#14024)
## Summary
Removes `Type::None` in favor of `KnownClass::NoneType.to_instance(…)`.
closes #13670
## Performance
There is a -4% performance regression on our red-knot benchmark. This is due to the fact that we now have to import `_typeshed` as a module, and infer types.
## Test Plan
Existing tests pass.
