Bring Host build into separate project

build_projects/shared-build-targets-utils/Utils/DotNetCli.cs

@@ -0,0 +1,70 @@
+using System;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices;
+using Microsoft.DotNet.Cli.Build.Framework;
+using Microsoft.DotNet.InternalAbstractions;
+
+namespace Microsoft.DotNet.Cli.Build
+{
+    public class DotNetCli
+    {
+        public static readonly DotNetCli Stage0 = new DotNetCli(GetStage0Path());
+        public static readonly DotNetCli Stage1 = new DotNetCli(Dirs.Stage1);
+        public static readonly DotNetCli Stage2 = new DotNetCli(Dirs.Stage2);
+
+        public string BinPath { get; }
+
+        public DotNetCli(string binPath)
+        {
+            BinPath = binPath;
+        }
+
+        public Command Exec(string command, params string[] args)
+        {
+            var newArgs = args.ToList();
+            newArgs.Insert(0, command);
+
+            if (EnvVars.Verbose)
+            {
+                newArgs.Insert(0, "-v");
+            }
+
+            return Command.Create(Path.Combine(BinPath, $"dotnet{Constants.ExeSuffix}"), newArgs);
+        }
+
+        public Command Restore(params string[] args) => Exec("restore", args);
+        public Command Build(params string[] args) => Exec("build", args);
+        public Command Pack(params string[] args) => Exec("pack", args);
+        public Command Test(params string[] args) => Exec("test", args);
+        public Command Publish(params string[] args) => Exec("publish", args);
+
+        public string GetRuntimeId()
+        {
+            string info = Exec("", "--info").CaptureStdOut().Execute().StdOut;
+            string rid = Array.Find<string>(info.Split(Environment.NewLine.ToCharArray()), (e) => e.Contains("RID:"))?.Replace("RID:", "").Trim();
+
+            if (string.IsNullOrEmpty(rid))
+            {
+                throw new BuildFailureException("Could not find the Runtime ID from Stage0 --info or --version");
+            }
+
+            return rid;
+        }
+
+        private static string GetStage0Path()
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return Path.Combine(Directory.GetCurrentDirectory(), ".dotnet_stage0",
+                    RuntimeEnvironment.OperatingSystemPlatform.ToString(),
+                    RuntimeEnvironment.RuntimeArchitecture);
+            }
+            else
+            {
+                return Path.Combine(Directory.GetCurrentDirectory(), ".dotnet_stage0", RuntimeEnvironment.OperatingSystemPlatform.ToString());
+            }
+
+        }
+    }
+}