WIP: JSON enrollment importer #3896

Job	Run time
Build wheel	1m 41s
Formatting	1m 35s
Backup process	2m 57s
Linter	2m 15s
Build nix environment on MacOS	3m 33s
MyPy	1m 37s
Test + Coverage	3m 24s
Test Frontend	3m 25s
Test (shuffled order)	2m 26s
Test if testdata is up to date	1m 58s
Test Typescript	1m 39s
Install wheel with system Python	13s
	26m 43s

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