Feature/connect cancel (#74)

* Implemented connection cancellation

* Made connect requests return immediately and created a separate connection complete notification

* Fix spelling

* Fix sorting

* Add separate lock for cancellation source map

src/Microsoft.SqlTools.ServiceLayer/Connection/Contracts/ConnectionCompleteNotification.cs

@@ -0,0 +1,61 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.ServiceLayer.Hosting.Protocol.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.Connection.Contracts
+{
+    /// <summary>
+    /// Parameters to be sent back with a connection complete event
+    /// </summary>
+    public class ConnectionCompleteParams
+    {
+        /// <summary>
+        /// A URI identifying the owner of the connection. This will most commonly be a file in the workspace
+        /// or a virtual file representing an object in a database.         
+        /// </summary>
+        public string OwnerUri { get; set;  }
+
+        /// <summary>
+        /// A GUID representing a unique connection ID
+        /// </summary>
+        public string ConnectionId { get; set; }
+
+        /// <summary>
+        /// Gets or sets any detailed connection error messages.
+        /// </summary>
+        public string Messages { get; set; }
+
+        /// <summary>
+        /// Error message returned from the engine for a connection failure reason, if any.
+        /// </summary>
+        public string ErrorMessage { get; set; }
+
+        /// <summary>
+        /// Error number returned from the engine for connection failure reason, if any.
+        /// </summary>
+        public int ErrorNumber { get; set; }
+
+        /// <summary>
+        /// Information about the connected server.
+        /// </summary>
+        public ServerInfo ServerInfo { get; set; }
+
+        /// <summary>
+        /// Gets or sets the actual Connection established, including Database Name
+        /// </summary>
+        public ConnectionSummary ConnectionSummary { get; set; }
+    }
+
+    /// <summary>
+    /// ConnectionComplete notification mapping entry 
+    /// </summary>
+    public class ConnectionCompleteNotification
+    {
+        public static readonly 
+            EventType<ConnectionCompleteParams> Type =
+            EventType<ConnectionCompleteParams>.Create("connection/complete");
+    }
+}