User creation handler clean-ups (#1867)

* Wire up init user message

* Send schema list

* Load database roles

* Add create user

* Add a delete user handler and format service file

src/Microsoft.SqlTools.ServiceLayer/Management/Common/DataContainer.cs

@@ -749,7 +749,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Management
                     throw new InvalidOperationException();
                 }
 
-                // NOTE: ServerConnection property will constuct the object if needed
+                // NOTE: ServerConnection property will construct the object if needed
                 m_server ??= new Server(ServerConnection);
             }
         }