Fix leading trivia handling in ClassVisitor, add test comment at the end of existing trivia

Author: machibuse

Source/Porticle.Grpc.TypeMapper/ClassVisitor.cs

@@ -15,7 +15,7 @@ public class ClassVisitor : CSharpSyntaxRewriter
             return node;
 
         // Add marker
-        var trivia = SyntaxFactory.TriviaList(SyntaxFactory.Comment("/// <remark>" + marker + "</remark>"), SyntaxFactory.LineFeed).AddRange(node.GetLeadingTrivia());
+        var trivia = node.GetLeadingTrivia().Add(SyntaxFactory.Comment("/// <remark>" + marker + "</remark>")).Add(SyntaxFactory.CarriageReturnLineFeed);
         node = node.WithLeadingTrivia(trivia);
 
         var propertyVisitor = new PropertyVisitor();

Source/Porticle.Grpc.UnitTests/Test.proto

@@ -31,6 +31,9 @@ message TestMessageMapped {
   optional TestEnum enum_optional = 7;
 }
 
+//////////////////////////////////////////////
+// Test comment to check marker comment 
+//////////////////////////////////////////////
 message TestMessageEnum1 {
   optional TestEnum enum_optional = 7;
 }