dotnet-new csproj templates (#4382)

Make csproj templates first-class in dotnet-new.

TestAssets/TestProjects/ProjectJsonWebTemplate/Controllers/HomeController.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc;
+
+namespace WebApplication.Controllers
+{
+    public class HomeController : Controller
+    {
+        public IActionResult Index()
+        {
+            return View();
+        }
+
+        public IActionResult About()
+        {
+            ViewData["Message"] = "Your application description page.";
+
+            return View();
+        }
+
+        public IActionResult Contact()
+        {
+            ViewData["Message"] = "Your contact page.";
+
+            return View();
+        }
+
+        public IActionResult Error()
+        {
+            return View();
+        }
+    }
+}