Prefer RawRepresentable fix-its that don't require an extra conversion
That is, if a type has a raw value of Int, and the function being
called has overloads for both Int and UInt, we always want to offer a
fix-it that leads to the 'Int' overload, not insert a conversion to
UInt that might be incorrect.
More https://bugs.swift.org/browse/SR-8150.