Rollup merge of #77640 - ethanboxx:int_error_matching_attempt_2, r=KodrAus

Refactor IntErrorKind to avoid "underflow" terminology

This PR is a continuation of #76455

# Changes

- `Overflow` renamed to `PosOverflow` and `Underflow` renamed to `NegOverflow` after discussion in #76455
- Changed some of the parsing code to return `InvalidDigit` rather than `Empty` for strings "+" and "-". https://users.rust-lang.org/t/misleading-error-in-str-parse-for-int-types/49178
- Carry the problem `char` with the `InvalidDigit` variant.
- Necessary changes were made to the compiler as it depends on `int_error_matching`.
- Redid tests to match on specific errors.

r? ```@KodrAus```

compiler/rustc_middle/src/middle/limits.rs

@@ -48,10 +48,12 @@ fn update_limit(
                         .unwrap_or(attr.span);
 
                     let error_str = match e.kind() {
-                        IntErrorKind::Overflow => "`limit` is too large",
+                        IntErrorKind::PosOverflow => "`limit` is too large",
                         IntErrorKind::Empty => "`limit` must be a non-negative integer",
                         IntErrorKind::InvalidDigit => "not a valid integer",
-                        IntErrorKind::Underflow => bug!("`limit` should never underflow"),
+                        IntErrorKind::NegOverflow => {
+                            bug!("`limit` should never negatively overflow")
+                        }
                         IntErrorKind::Zero => bug!("zero is a valid `limit`"),
                         kind => bug!("unimplemented IntErrorKind variant: {:?}", kind),
                     };