BESANCON: create login method in module

The Besancon portal now requires a user to be logged in before accessing the model forms therefore a login method needs to be implemented in the Besancon module.

Start by locating the Besancon module and its model-form access entry points. Determine how the portal login must be performed before those forms can be accessed, then verify that the module can authenticate and still retrieve the model forms afterward.

Written by the indexing model from the issue text.