Split `settings.BASE_DIR` into `MODULE` and `DATADIR` #3725

Job	Run time
Backup process	2m 53s
Compile Scss	1m 22s
Formatting	1m 23s
Linter	1m 20s
Build nix environment on MacOS	2m 1s
MyPy	1m 21s
Render Html pages	1m 21s
Test + Coverage	2m 29s
Test (shuffled order)	2m 6s
Test Typescript	1m 57s
	18m 13s

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