refs #15161 [fid_bbi] contact form

* add bbi contact form
** set link to contact form in footer
** add static contact.phtml form
** add translations
* use default vufind feedback functionality for contact form
** add / correct translations for contact form
** activate FeedbackForms and configure FeedbackForms.yaml
** change link in footer
** remove link in header to activated feedback form
* add privacy policy check to derived contact / feedback form
* modify FeedbackForms.yaml of alpha and staging for policy check
* check for required attribute of policy check in form
* configure Alpha Mailer