Add Loket API `AbsenceProgress` available as a view

Please make the Loket API Absence Progress data available for routine OData consumption via the lnr (loket.nl (REST)) views.

This would help us greatly to calculate the sick leave progress, as the currently available data falls short.

Here is the query that could be used:

select apsprog.* prefix with 'apsprog_'
,      epr.id epr_id
,      epe.id epe_id
,      aps.id aps_id 
from   EmployersByUserId epr 
join   EmployeesByEmployerId(epr.id) epe 
join   AbsencesByEmployeeId(epe.id) aps 
join   AbsenceProgressByAbsenceId(aps.id) apsprog

Deze Loket absence data is vanaf release 20.1.439 te vinden in Invantive Cloud als de view EmployeeAbsenceProgresses.