allow ResourceForm`s `#for` factory method to find Collection forms
allow ResourceForm`s `#for` factory method to find Collection forms

map `Hyrax::PcdmCollection` to `Hyrax::Forms::PcdmCollectionForm` for the
factory method's purposes.

samvera/hyrax,samvera/hyrax,samvera/hyrax,samvera/hyrax