Adds an end-to-end (e2e) test case for:
* Emptying a post from the trash.
* Restoring a post from the trash.
Props pavanpatil1, pooja1210, justinahinon, kevin940726.
Fixes#54843.
git-svn-id: https://develop.svn.wordpress.org/trunk@52839 602fd350-edb4-49c9-b593-d223f7449a82