Fix lack of trailing italics.

Author: 333fred

src/OmniSharp.Roslyn.CSharp/Helpers/MarkdownHelpers.cs

@@ -198,6 +198,11 @@ public static void TaggedTextToMarkdown(
                 endBlock();
             }
 
+            if (!brokeLine && markdownFormat == MarkdownFormat.Italicize)
+            {
+                stringBuilder.Append("_");
+            }
+
             return;
 
             void addText(string text)

tests/OmniSharp.Roslyn.CSharp.Tests/QuickInfoProviderFacts.cs

@@ -709,6 +709,23 @@ public static void A()
             Assert.Equal("```csharp\nvoid Program.B()\n```\n\n\\*This should be escaped\\*", response.Markdown);
         }
 
+        [Fact]
+        public async Task NullableIsItalicized()
+        {
+            string content = @"
+#nullable enable
+class Program
+{
+    public static void A(string s)
+    {
+        _ = s$$;
+    }
+
+}";
+            var response = await GetTypeLookUpResponse(content);
+            Assert.Equal("```csharp\n(local) string? s\n```\n\n_'s' is not null here._", response.Markdown);
+        }
+
         private async Task<QuickInfoResponse> GetTypeLookUpResponse(string content)
         {
             TestFile testFile = new TestFile("dummy.cs", content);