Write tests to check rules_forms_event_info array structure after enabling forms

Due to the errors reported at #1447328: Error Message/Notice on Views Exposed Filter use, I think we should add a test to check the structure of the rules_forms_event_info Drupal variable after enabling and evaluating multiple forms. The form elements don't necessarily need to be checked. But what does need to be checked is that each entry has a form ID, label, and necessary arrays like the elements array, and each key should be a string. This test can help prevent improper Rules events as are described in the issue above.