Use C# 13 overload resolution attribute to improve friendly overloads

[AArnott]

As brought up in #1049 (comment)

C# supports using a polyfill attribute, so this works on any target framework. But it does require C# 13 to reference the attribute on an API or an error results, so CsWin32 only emits or uses the attribute when C# 13 is in operation.

[Copilot]

Copilot reviewed 5 out of 8 changed files in this pull request and generated 1 comment.

Files not reviewed (3)

• src/Microsoft.Windows.CsWin32/SimpleSyntaxFactory.cs: Evaluated as low risk
• src/Microsoft.Windows.CsWin32/Generator.cs: Evaluated as low risk
• src/Microsoft.Windows.CsWin32/Generator.FriendlyOverloads.cs: Evaluated as low risk

Comments suppressed due to low confidence (4)

src/Microsoft.Windows.CsWin32/Generator.Templates.cs:42

• [nitpick] The method name TryFetchTemplate is ambiguous as there is already a method with the same name but different parameters. Consider renaming it to TryFetchTemplateCompilationUnit for clarity.

private static bool TryFetchTemplate(string name, Generator? generator, [NotNullWhen(true)] out CompilationUnitSyntax? compilationUnit)

src/Microsoft.Windows.CsWin32/Generator.Templates.cs:44

• The FetchTemplateText method should handle null values correctly. Ensure that null values are appropriately managed to avoid potential null reference exceptions.

string? template = FetchTemplateText(name);

src/Microsoft.Windows.CsWin32/Generator.Templates.cs:51

• The new method TryFetchTemplate should be covered by tests to ensure it works as expected. Add test cases to verify its functionality.

compilationUnit = SyntaxFactory.ParseCompilationUnit(template, options: generator?.parseOptions) ?? throw new GenerationFailedException($"Unable to parse compilation unit from a template: {name}");

test/Microsoft.Windows.CsWin32.Tests/GeneratorTestBase.cs:227

• Verify that the StringSyntax attribute is correctly supported and used in the context of the project.

protected CSharpCompilation AddCode([StringSyntax("c#-test")] string code, string? fileName = null, CSharpCompilation? compilation = null)