Custom logger for MSBuild to receive telemetry events (#4551)

* Upgrade MSBuild references to 15.1.0-preview-000370-00

* Custom logger for MSBuild to receive telemetry events

Had to make the telemetry session ID a static variable so that the forwarding app could use it.

I've tested this all manually and will be writing tests after everyone signs off on the implementation here.

src/dotnet/commands/dotnet-msbuild/MSBuildLogger.cs

@@ -0,0 +1,52 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+using Microsoft.DotNet.Cli;
+using Microsoft.DotNet.Cli.Utils;
+using Microsoft.DotNet.Configurer;
+
+namespace Microsoft.DotNet.Tools.MSBuild
+{
+    public sealed class MSBuildLogger : Logger
+    {
+        private readonly INuGetCacheSentinel _sentinel = new NuGetCacheSentinel();
+        private readonly ITelemetry _telemetry;
+
+        public MSBuildLogger()
+        {
+            string sessionId = Environment.GetEnvironmentVariable(MSBuildForwardingApp.TelemetrySessionIdEnvironmentVariableName);
+
+            if (sessionId != null)
+            {
+                _telemetry = new Telemetry(_sentinel, sessionId);
+            }
+        }
+
+        public override void Initialize(IEventSource eventSource)
+        {
+            if (_telemetry != null)
+            {
+                IEventSource2 eventSource2 = eventSource as IEventSource2;
+
+                if (eventSource2 != null)
+                {
+                    eventSource2.TelemetryLogged += (sender, telemetryEventArgs) =>
+                    {
+                        Console.WriteLine($"Received telemetry event '{telemetryEventArgs.EventName}'");
+                        _telemetry.TrackEvent(telemetryEventArgs.EventName, telemetryEventArgs.Properties, measurements: null);
+                    };
+                }
+            }
+        }
+
+        public override void Shutdown()
+        {
+            _sentinel?.Dispose();
+
+            base.Shutdown();
+        }
+    }
+}