Bring Host build into separate project

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

@@ -0,0 +1,28 @@
+using System;
+using System.IO;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.DotNet.Cli.Build
+{
+    public static class JsonUtils
+    {
+        public static JObject ReadProject(string projectJsonPath)
+        {
+            using (TextReader projectFileReader = File.OpenText(projectJsonPath))
+            {
+                var projectJsonReader = new JsonTextReader(projectFileReader);
+
+                var serializer = new JsonSerializer();
+                return serializer.Deserialize<JObject>(projectJsonReader);
+            }
+        }
+
+        public static void WriteProject(JObject projectRoot, string projectJsonPath)
+        {
+            string projectJson = JsonConvert.SerializeObject(projectRoot, Formatting.Indented);
+
+            File.WriteAllText(projectJsonPath, projectJson + Environment.NewLine);
+        }
+    }
+}