As far as I know this change is largely non-functional, largely because
of https://github.com/astral-sh/ty/issues/1601
It's possible some of these like `Type::KnownInstance` produce something
useful sometimes. `LiteralString` is a new introduction, although its
goto-type jumps to `str` which is a bit sad (considering that part of
the SpecialForm discourse for now).
Also wrt the generics testing followup: turns out the snapshot tests
were full of those already.
78ce17ce8f