gh-103763: Implement PEP 695 (#103764)

This implements PEP 695, Type Parameter Syntax. It adds support for:

- Generic functions (def func[T](): ...)
- Generic classes (class X[T](): ...)
- Type aliases (type X = ...)
- New scoping when the new syntax is used within a class body
- Compiler and interpreter changes to support the new syntax and scoping rules 

Co-authored-by: Marc Mueller <[email protected]>
Co-authored-by: Eric Traut <[email protected]>
Co-authored-by: Larry Hastings <[email protected]>
Co-authored-by: Alex Waygood <[email protected]>