Purpose
=======

In Belgium, we need to support some partial time on 2 weeks.
For instance, a mid time, means you could work on monday, tuesday
and wednesday on week1 and monday and tuesday on week 2. Others payroll
softwares manage this.

Specification
=============

Add a checkbox on resource calendar to manage 2 weeks. --> Consider even/odd weeks.
Add sections on calendars (Like sales orders)
Modify methods in resources to apply this behavor generically.

Check that attendances aren't overlapped

Write an integration test for holidays - benefits - payslip
to check all this, + "credit temps" and wage modification.

Note
====

For the sake of simplicity, we only manage calendars over 2 weeks
to consider the odd/even weeks and keep an easy implementation.
For more complicated calendars (eg: over a months with specific targetted days),
it's better to create specific allocation requests and apply specific leaves
for those days, as it would be the case for parental leaves.

closes odoo/odoo#31674

Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>