Simplify target grouping comparer

Replace the custom `TargetNameExtensionComparer` type in `VerifyEngine` with an inline `EqualityComparer<Target>.Create(...)` instance. This keeps the grouping behavior the same while reducing dedicated comparer boilerplate.

Author: SimonCropp

src/Verify/Verifier/VerifyEngine.cs

@@ -82,7 +82,7 @@ async Task Inner(FilePair file, Target target)
             HandleCompareResult(result, file);
         }
 
-        foreach (var group in targetList.GroupBy(_ => _, TargetNameExtensionComparer.Instance))
+        foreach (var group in targetList.GroupBy(_ => _, targetNameExtensionComparer))
         {
             var targets = group.ToList();
             if (targets.Count == 1)
@@ -296,14 +296,6 @@ async Task<bool> ProcessNew()
     static void AcceptChanges(in FilePair file) =>
         File.Move(file.ReceivedPath, file.VerifiedPath, true);
 
-    private sealed class TargetNameExtensionComparer : IEqualityComparer<Target>
-    {
-        public static readonly TargetNameExtensionComparer Instance = new();
-
-        public bool Equals(Target x, Target y) =>
-            (x.Name ?? "") == (y.Name ?? "") && x.Extension == y.Extension;
-
-        public int GetHashCode(Target obj) =>
-            (obj.Name ?? "", obj.Extension).GetHashCode();
-    }
+    static readonly IEqualityComparer<Target> targetNameExtensionComparer =
+        EqualityComparer<Target>.Create(_ => (_.Name ?? "", _.Extension));
 }