Fix 4655: Migrate errors are not getting put in formatted output (#4718)

* Fix 4655: Migrate errors are not getting put in formatted output

* Move test asset to NonRestoredTestProjects

* use group test asset manager: NonRestoredTestProjects

TestAssets/NonRestoredTestProjects/MigrateAppWithMissingDep/MyApp/Program.cs

@@ -0,0 +1,10 @@
+namespace ConsoleApplication
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+        }
+    }
+}
+

TestAssets/NonRestoredTestProjects/MigrateAppWithMissingDep/MyApp/project.json

@@ -0,0 +1,20 @@
+{
+  "version": "1.0.0-*",
+  "buildOptions": {
+    "emitEntryPoint": true
+  },
+
+  "dependencies": {
+    "Microsoft.NETCore.App": {
+      "type": "platform",
+      "version": "1.0.1"
+    },
+    "MyLib": "1.0.0-*"
+  },
+
+  "frameworks": {
+    "netcoreapp1.0": {
+      "imports": "dnxcore50"
+    }
+  }
+}

TestAssets/NonRestoredTestProjects/MigrateAppWithMissingDep/MyLib/NotUsedButDoNotRemove.cs

@@ -0,0 +1,5 @@
+// This file needs to be here as this error does not repro if the MyLib folder doesn't exist
+// Since git does not keep track of folders and files only, this folder needs to contain any file.
+namespace MyLib
+{
+}