Fix property backing field conversion for virtual properties

This commit fixes issue #827 where accessing the auto-generated backing
field (e.g. `_Prop`) of an overridable (virtual) property in VB.NET was
incorrectly converted to the virtual property access (`Prop`) in C#.

It now correctly maps these accesses to the explicitly generated
non-virtual backing property `MyClassProp` and ensures that the
MyClassProp property is correctly generated when such an access occurs.

A test case has been added to MemberTests.cs to verify the correct
translation of such field access.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: GrahamTheCoder

CodeConverter/CSharp/DeclarationNodeVisitor.cs

@@ -700,7 +700,7 @@ private static HashSet<string> GetMyClassAccessedNames(VBSyntax.ClassBlockSyntax
         foreach (var id in identifierNames)
         {
             var symbolInfo = semanticModel.GetSymbolInfo(id);
-            if (symbolInfo.Symbol is IFieldSymbol fieldSymbol && fieldSymbol.AssociatedSymbol != null && fieldSymbol.AssociatedSymbol.IsVirtual && !fieldSymbol.AssociatedSymbol.IsAbstract)
+            if (symbolInfo.Symbol is IFieldSymbol fieldSymbol && fieldSymbol.AssociatedSymbol != null && fieldSymbol.AssociatedSymbol.IsVirtual && !fieldSymbol.AssociatedSymbol.IsAbstract && !id.Identifier.Text.StartsWith("MyClass", StringComparison.OrdinalIgnoreCase))
             {
                 accessedTextNames.Add(fieldSymbol.AssociatedSymbol.Name);
             }