Show expected and available ABI tags in resolver errors (#10527)

## Summary

The idea here is to show both (1) an example of a compatible tag and (2)
the tags that were available, whenever we fail to resolve due to an
abscence of matching wheels.

Closes https://github.com/astral-sh/uv/issues/2777.

crates/uv-resolver/src/requires_python.rs

@@ -7,6 +7,7 @@ use pubgrub::Range;
 use uv_distribution_filename::WheelFilename;
 use uv_pep440::{release_specifiers_to_ranges, Version, VersionSpecifier, VersionSpecifiers};
 use uv_pep508::{MarkerExpression, MarkerTree, MarkerValueVersion};
+use uv_platform_tags::AbiTag;
 
 /// The `Requires-Python` requirement specifier.
 ///
@@ -303,6 +304,23 @@ impl RequiresPython {
         &self.range
     }
 
+    /// Returns a wheel tag that's compatible with the `Requires-Python` specifier.
+    pub fn abi_tag(&self) -> Option<AbiTag> {
+        match self.range.lower().as_ref() {
+            Bound::Included(version) | Bound::Excluded(version) => {
+                let major = version.release().first().copied()?;
+                let major = u8::try_from(major).ok()?;
+                let minor = version.release().get(1).copied()?;
+                let minor = u8::try_from(minor).ok()?;
+                Some(AbiTag::CPython {
+                    gil_disabled: false,
+                    python_version: (major, minor),
+                })
+            }
+            Bound::Unbounded => None,
+        }
+    }
+
     /// Simplifies the given markers in such a way as to assume that
     /// the Python version is constrained by this Python version bound.
     ///