Add export functionality to absence statistics page

changed milestone to /AlekSIS%"[NLnet #3] Implement support for absences"

added part::frontend type::feature labels

removed milestone /AlekSIS%"[NLnet #3] Implement support for absences"

changed milestone to /AlekSIS%"[NLnet #3] Implement statistical reports and functions"

added source::customer::kath label

added prio::2 label

PDF-Export or CSV?

PDF export, the functionality for this is already prepared by !422 (merged).

removed milestone /AlekSIS%"[NLnet #3] Implement statistical reports and functions"

assigned to @hansegucker

created branch 267-add-export-functionality-to-absence-statistics-page to address this issue

mentioned in merge request !477 (merged)

closed with commit f84e6bc7

mentioned in commit f84e6bc7