Fix an issue with usings

Author: jaredpar

src/Microsoft.DotNet.CodeFormatting/Rules/HasUsingsOutsideOfNamespaceFormattingRule.cs

@@ -31,6 +31,11 @@ public async Task<Document> ProcessAsync(Document document, CancellationToken ca
                 if (namespaceWithUsings == null)
                     break;
 
+                // Moving a using with an alias out of a namespace is an operation which requires
+                // semantic knowledge to get correct.
+                if (namespaceWithUsings.Usings.Any(x => x.Alias != null))
+                    return document;
+
                 // Remove nested usings
 
                 var emptyUsingList = SyntaxFactory.List<UsingDirectiveSyntax>();