[NLnet #3] Implement support for absences

Unstarted Issues (open and unassigned)

Ongoing Issues (open and assigned)

Completed Issues (closed)

AlekSIS-App-Kolego · Add default value to absence-reason-chip if none is provided
#16
AlekSIS-Core · Add generic labels for forms
#1035
AlekSIS-Core · Add short date format with weekday
#1034
AlekSIS-App-Alsijil · Add absence overview page
#264 part::frontend type::feature
AlekSIS-App-Alsijil · Add management of absence reasons
#262 part::backend part::frontend type::feature
AlekSIS-App-Alsijil · Add absence management to course book student dialog
#261 part::frontend type::feature