Sort extension members alphabetically within each extension block

[Copilot]

• Reorder Net60/EnumerableExtensionsTests.cs: Chunk → DistinctBy → ElementAt → ElementAtOrDefault → ExceptBy → FirstOrDefault (×2) → IntersectBy → LastOrDefault (×2) → Max → MaxBy → Min → MinBy → SingleOrDefault (×2) → Take → UnionBy → Zip (×2)
• Reorder Net80/CollectionExtensionsTests.cs: AddRange (×2) → CopyTo (×2) → InsertRange
• Reorder Net90/EnumerableExtensionsTests.cs: AggregateBy → CountBy → Index
• Reorder NetCore10/EnumerableExtensionsTests.cs: Append → Prepend
• Reorder NetCore20/CollectionExtensionsTests.cs: GetValueOrDefault → Remove (×2) → TryAdd (×2)
• Reorder NetCore20/EnumerableExtensionsTests.cs: SkipLast → TakeLast → ToHashSet
• Reorder NetCore21/MemoryExtensionsTests.cs: Array AsMemory (×3) → AsSpan (×3) → CopyTo(Memory) → CopyTo(Span); ArraySegment AsSpan; String AsMemory (×3) → AsSpan (×3); Span IndexOf → Reverse → SequenceEqual (×3); ReadOnlySpan IndexOf → SequenceEqual (×2)

[Tyrrrz]

@copilot please make sure that the order of test methods reflects the order of the actual members they're testing

[Copilot]

Pull request overview

This PR standardizes member ordering within C# extension blocks across PolyShim by sorting extension members alphabetically (keeping delegating overloads adjacent to the primary overloads), improving readability and consistency in the polyfill surface area.

Changes:

• Reordered extension methods in multiple polyfill files to be alphabetical within each extension block.
• Kept overload groupings intact (callee overloads adjacent to delegating overloads) while reordering.
• No functional logic changes intended; changes are organizational.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
PolyShim/Net60/EnumerableExtensions.cs	Alphabetized and regrouped LINQ extension polyfills within the IEnumerable<T> extension block.
PolyShim/Net80/CollectionExtensions.cs	Reordered AddRange / CopyTo / InsertRange within the List<T> extension block.
PolyShim/Net90/EnumerableExtensions.cs	Reordered AggregateBy, CountBy, and Index within the IEnumerable<T> extension block.
PolyShim/NetCore10/EnumerableExtensions.cs	Swapped Append / Prepend ordering within the IEnumerable<T> extension block.
PolyShim/NetCore20/CollectionExtensions.cs	Reordered Remove and TryAdd within the IDictionary<TKey, TValue> extension block.
PolyShim/NetCore20/EnumerableExtensions.cs	Reordered SkipLast / TakeLast within the IEnumerable<T> extension block.
PolyShim/NetCore21/MemoryExtensions.cs	Reordered AsMemory/AsSpan groups and CopyTo overloads; moved Reverse above SequenceEqual in the Span<T> block.
PolyShim/NetCore30/TaskAsyncEnumerableExtensions.cs	Reordered ConfigureAwait and WithCancellation within the IAsyncEnumerable<T> extension block.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov]

Codecov Report

❌ Patch coverage is 98.61111% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.68%. Comparing base (7b40ef0) to head (7bb55a3).
⚠️ Report is 1 commits behind head on prime.

Files with missing lines	Patch %	Lines
PolyShim/NetCore21/MemoryExtensions.cs	78.57%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            prime     #121   +/-   ##
=======================================
  Coverage   90.68%   90.68%           
=======================================
  Files         286      286           
  Lines        4982     4982           
  Branches      406      406           
=======================================
  Hits         4518     4518           
  Misses        372      372           
  Partials       92       92           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.