Move `manage.py` content to `evap.main` (#2387) #3814

Job	Run time
Linter	2m 9s
Test (shuffled order)	2m 18s
Formatting	1m 28s
Backup process	3m 6s
MyPy	1m 29s
Compile Scss	1m 38s
Test + Coverage	2m 45s
Build nix environment on MacOS	3m 36s
Render Html pages	1m 47s
Test Typescript	1m 59s
	22m 15s

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