CompileTargets moved to MSBuild

CompileTargets moved to MSBuild. Still need to work on input/outputs, refactoring of targets, specially around CompileStage and moving some of the tasks back to msbuild instead of C# code.

build_projects/dotnet-cli-build/FixModeFlags.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.Compression;
+using System.Runtime.InteropServices;
+using System.Net.Http;
+using Microsoft.Build.Utilities;
+using Microsoft.DotNet.Cli.Build.Framework;
+using Microsoft.DotNet.InternalAbstractions;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+
+using static Microsoft.DotNet.Cli.Build.Framework.BuildHelpers;
+
+namespace Microsoft.DotNet.Cli.Build
+{
+    public class FixModeFlags : Task
+    {
+        public string Dir { get; set; }
+
+        public override bool Execute()
+        {
+            FS.FixModeFlags(Dir);
+
+            return true;
+        }
+    }
+}