4833: Separating parsing of `for` in predicates and types r=matklad a=matthewjasper
We now correctly accept `for<'a> (&'a F): Fn(&'a str)` in a where clause and correctly reject `for<'a> &'a u32` as a type.
Co-authored-by: Matthew Jasper <mjjasper1@gmail.com>
36353bb182