adding a new event for when definition is requested (#167)

* sending telemetry events for intellisense usage

src/Microsoft.SqlTools.ServiceLayer/LanguageServices/Contracts/TelemetryNotification.cs

@@ -0,0 +1,59 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Collections.Generic;
+using Microsoft.SqlTools.ServiceLayer.Hosting.Protocol.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.LanguageServices.Contracts
+{
+    public class TelemetryProperties
+    {
+        public string EventName { get; set; }
+
+        /// <summary>
+        /// Telemetry properties
+        /// </summary>
+        public Dictionary<string, string> Properties { get; set; }
+
+        /// <summary>
+        /// Telemetry measures
+        /// </summary>
+        public Dictionary<string, double> Measures { get; set; }
+    }
+
+    /// <summary>
+    /// Parameters sent back with an IntelliSense ready event
+    /// </summary>
+    public class TelemetryParams
+    {
+        public TelemetryProperties Params { get; set; }
+    }
+
+    /// <summary>
+    /// Event sent when the language service needs to add a telemetry event
+    /// </summary>
+    public class TelemetryNotification
+    {
+        public static readonly
+            EventType<TelemetryParams> Type =
+            EventType<TelemetryParams>.Create("telemetry/event");
+    }
+
+    /// <summary>
+    /// List of telemetry events
+    /// </summary>
+    public static class TelemetryEventNames
+    {
+        /// <summary>
+        /// telemetry event name for auto complete response time
+        /// </summary>
+        public const string IntellisenseQuantile = "IntellisenseQuantile";
+
+        /// <summary>
+        /// telemetry even name for when definition is requested
+        /// </summary>
+        public const string PeekDefinitionRequested = "PeekDefinitionRequested";
+    } 
+}