& use in DocumentationBatchCreateOrUpdateMutation & AbsencesBatchCreateMutation.

& share between query & mutation.

& use documentations instead of lesson-events

into get_documentations_for_events
& get_for_coursebook
This makes it reusable for further purposes (absences).

Did nothing in this case previously

Currently translated at 30.7% (12 of 39 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/uk/

Currently translated at 30.7% (12 of 39 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/ru/

Currently translated at 100.0% (39 of 39 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/de/

Currently translated at 100.0% (318 of 318 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil/de/

& do the TODO.
Also leave a pointer how to improve it (even) more.

It does not have to be the currentDate. This holds only for the first day.

Updating the hash fragment causes a small delay while scrolling.
=> Update only after user finished scrolling.
Uses requestIdleCallback
which is not ready for prime time in Safari. But should work elsewhere.