Revert "removed ember-focus-trap from test-app"

This reverts commit c6dd6ff.

Author: SanderKnauff

test-app/package.json

@@ -68,6 +68,7 @@
     "ember-compatibility-helpers": "1.2.7",
     "ember-element-helper": "0.8.8",
     "ember-eslint-parser": "0.5.13",
+    "ember-focus-trap": "1.1.1",
     "ember-load-initializers": "3.0.1",
     "ember-on-helper": "0.1.0",
     "ember-page-title": "9.0.3",