based type annotation improvements (bare literal, tuple literal)

They should work in:
- `cast`
- `assert_type`
- Make basedtyping versions of the things in `typing` that support bare literals.

Start by locating the implementations of cast and assert_type, then identify the basedtyping counterparts to typing constructs that support bare literals. Trace how bare literals and tuple literals are represented in these entry points; done means the requested forms work consistently across the named APIs and their basedtyping versions.

Written by the indexing model from the issue text.