R1:899abf7a2b53

Redirect back to object after clicking "Log In to Comment" and login

Summary:
`PhabricatorApplicationTransactionCommentView` performs `$uri = id(new PhutilURI('/login/'))->replaceQueryParam('next', (string)$this->getRequestURI())` but the constructor call in `PhabricatorEditEngine` does not set any `RequestURI` so the `Log In to Comment` button at the bottom of an object view does not redirect back to the object URI after login.

Thus pass a `RequestURI` to `PhabricatorApplicationTransactionCommentView`…