[server] extract creating a new cnxset in a _new_cnxset() helper
So we can move logic specific to _CnxSetPool here.
.. _login_module:
:mod:`cubicweb.pyramid.login`
-----------------------------
.. automodule:: cubicweb.pyramid.login
.. autofunction:: includeme
Views
-----
.. autofunction:: login_form
.. autofunction:: login_password_login
.. autofunction:: login_already_loggedin