In https://github.com/odoo/odoo/pull/114827, a new attribute was added in
calendar views to allow passing the id of a form view that is used internally
in the calendar module to show a different form view when quick_creating an
event.
task-3129030
closesodoo/documentation#4221
Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>