Start to port main gut of the foundation

Toolkit.Foundation/Extensions/IHostBuilderExtensions.cs

@@ -0,0 +1,18 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
+namespace Toolkit.Foundation
+{
+    public static class IHostBuilderExtensions
+    {
+        public static IHostBuilder UseContentRoot(this IHostBuilder hostBuilder, string contentRoot, bool createDirectory)
+        {
+            if (!Directory.Exists(contentRoot) && createDirectory)
+            {
+                Directory.CreateDirectory(contentRoot);
+            }
+
+            return hostBuilder.UseContentRoot(contentRoot);
+        }
+    }
+}