Allow any numeric range to become a float

Currently things like `1 / 200` lead to a miscompilation because we type
`200` (and as a result, both `1` and the division result) as a ranged
number with width >= U8. During mono that forces the number to become an
`I64` because our logic was that a ranged number can only become a float
if it's at least as wide as an I8. But this is incorrect; as long as the
type is wrapped in `Frac` constructor and it's a ranged number (and not
a ranged int), it should become a fractional type.

```
» 1 / 200

0.005 : Float *
```

Closes #4047

crates/compiler/mono/src/layout.rs

@@ -2181,7 +2181,7 @@ pub fn is_any_float_range(subs: &Subs, var: Variable) -> bool {
     let content = subs.get_content_without_compacting(var);
     matches!(
         content,
-        RangedNumber(NumAtLeastEitherSign(I8) | NumAtLeastSigned(I8)),
+        RangedNumber(NumAtLeastEitherSign(..) | NumAtLeastSigned(..)),
     )
 }