Avoid exception on missing ability, refs #7641
Fix partial call, refs #7726
Add other model for Finding Aid generation

This model (called 'bombardier' for the moment) adds full metadata
for all the archival descriptions in the selected collection/fonds.

- Renames 'sfu' XSL file to 'ead-pdf-sfu.xls'
- Adds XSL file for 'bombardier' model: 'ead-pdf-bombardier.xls'
- Fixes in helper-functions file
- Adds setting for FA model (migration/fixtures). Values are temporary
- Use setting on FA generation, selecting the associated XLS file

Refs #7723
Open/download Finding Aid in new tab

Refs #7723
Change Finding Aids filename, refs #7723

- Adds QubitSlug::getByObjectId static function
- Uses IO slug for the FA filename. If the slug doesn't exist
  it keeps using the id