VB -> C#: private partial methods do not compile

- Added unit test to SpecialConversionTests (not MethodStatementTests  as there is no statements)
-ISymbolExtensions.cs
  - CanHaveMethodBody & IsPartialMethodDefinition
  - Added check for IsPartialDefinition

#1097

Author: John Moreno

CodeConverter/Util/ISymbolExtensions.cs

@@ -75,12 +75,12 @@ public static bool IsPartialMethodImplementation(this ISymbol declaredSymbol)
 
     public static bool CanHaveMethodBody(this ISymbol declaredSymbol)
     {
-        return !(declaredSymbol is IMethodSymbol ms) || ms.PartialImplementationPart == null && !ms.IsExtern;
+        return !(declaredSymbol is IMethodSymbol ms) || (!ms.IsPartialDefinition && (ms.PartialImplementationPart == null && !ms.IsExtern));
     }
 
     public static bool IsPartialMethodDefinition(this ISymbol declaredSymbol)
     {
-        return declaredSymbol is IMethodSymbol ms && ms.PartialImplementationPart != null;
+        return declaredSymbol is IMethodSymbol ms && (ms.PartialImplementationPart != null || ms.IsPartialDefinition);
     }
 
     public static bool IsPartialClassDefinition(this ISymbol declaredSymbol)

Tests/CSharp/SpecialConversionTests.cs

@@ -402,4 +402,11 @@ End If
     }
 }");
     }
+
+    [Fact]
+    public async Task Issue1097_PartialMethodAsync()
+    {
+        await TestConversionVisualBasicToCSharpAsync(@"Partial Private Sub DummyMethod()
+    End Sub", @"partial void DummyMethod();");
+    }
 }