Set default relative path for Project Identity in Integration tests

src/VisualStudio/IntegrationTest/TestUtilities/Common/ProjectUtilities.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System.IO;
+
 namespace Microsoft.VisualStudio.IntegrationTest.Utilities.Common.ProjectUtils
 {
     public abstract class Identity
@@ -9,12 +11,23 @@ public abstract class Identity
 
     public class Project : Identity
     {
-        public Project(string name, string relativePath = null)
+        public Project(string name, string projectExtension = ".csproj", string relativePath = null)
         {
             Name = name;
-            RelativePath = relativePath;
+
+            if (string.IsNullOrWhiteSpace(relativePath))
+            {
+                RelativePath = Path.Combine(name, name + projectExtension);
+            }
+            else
+            {
+                RelativePath = relativePath;
+            }
         }
 
+        /// <summary>
+        /// This path is relative to the Solution file. Default value is set to ProjectName\ProjectName.csproj
+        /// </summary>
         public string RelativePath { get; }
     }