[ADD][14.0] resource_booking_simultaneous_human

[carmenbianca]

When a resource of type human is scheduled for a booking, they remain simultaneously available for other bookings.

The purpose of this module is bookings for events where a worker can split their attention between multiple attendants.

Internal task: https://gestion.coopiteasy.be/web#id=9879&action=475&active_id=434&model=project.task&view_type=form&menu_id=536