Converts WindowManagerTest.OpenWindow to aura-mus

mash/unittests_manifest.json

 {
   "name": "mash_unittests",
   "display_name": "Mash Unittests",
   "interface_provider_specs": {
     "service_manager:connector": {
       "requires": {
         "*": [ "app", "test" ],
-        "ash": [ "mus:window_manager" ]
+        "ash": [ "mus:window_manager" ],
+        "ui": [ "app" ]
       }
     }
   }
 }