Improve test coverage for IsMemberDeclaration method

[Youssef1313]

I don't think it's a good idea to update this one without knowing the change it introduce.

This whole method isn't covered in the tests. See how #48158 is green.

Originally posted by @Youssef1313 in #48137 (comment)

[Youssef1313]

After figuring out what this method affects, we need to decide whether to update it with init accessor or not.

[Youssef1313]

I could get test failures in #48158 by the last commit in it. But still, doesn't cover everything in the method.

[sharwell]

This is in reference to the following method:

roslyn/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/CSharp/Services/SyntaxFacts/CSharpSyntaxFacts.cs

Lines 1292 to 1334 in 60d89c9

	private static bool IsMemberDeclaration(SyntaxNode node)
	{
	// From the C# language spec:
	// class-member-declaration:
	// constant-declaration
	// field-declaration
	// method-declaration
	// property-declaration
	// event-declaration
	// indexer-declaration
	// operator-declaration
	// constructor-declaration
	// destructor-declaration
	// static-constructor-declaration
	// type-declaration
	switch (node.Kind())
	{
	// Because fields declarations can define multiple symbols "public int a, b;"
	// We want to get the VariableDeclarator node inside the field declaration to print out the symbol for the name.
	case SyntaxKind.VariableDeclarator:
	return node.Parent.Parent.IsKind(SyntaxKind.FieldDeclaration) ||
	node.Parent.Parent.IsKind(SyntaxKind.EventFieldDeclaration);
	case SyntaxKind.FieldDeclaration:
	case SyntaxKind.MethodDeclaration:
	case SyntaxKind.PropertyDeclaration:
	case SyntaxKind.GetAccessorDeclaration:
	case SyntaxKind.SetAccessorDeclaration:
	case SyntaxKind.EventDeclaration:
	case SyntaxKind.EventFieldDeclaration:
	case SyntaxKind.AddAccessorDeclaration:
	case SyntaxKind.RemoveAccessorDeclaration:
	case SyntaxKind.IndexerDeclaration:
	case SyntaxKind.OperatorDeclaration:
	case SyntaxKind.ConversionOperatorDeclaration:
	case SyntaxKind.ConstructorDeclaration:
	case SyntaxKind.DestructorDeclaration:
	return true;
	default:
	return false;
	}
	}