BibFormat: load bfe_elements in Jinja env
BibFormat: load bfe_elements in Jinja env

* Fix issue with bibreformat creating empty pre-formatted records,
  caused by bibformat elements not being loaded.

Co-authored-by: Jiri Kuncar <2bdffcb416fed3002465740d19a053a39918cbe5@cern.ch>

tiborsimko/invenio-formatter,tiborsimko/invenio-formatter,inveniosoftware/invenio-formatter,tiborsimko/invenio-formatter,inveniosoftware/invenio-formatter,inveniosoftware/invenio-formatter