Introduce “manage.py initialize” interactive command (#3117)

- Create/update superuser
- Set wagtail site domains

```
❯ ./manage.py initialize
Provide the details below to initialize Hypha Site. Press enter to keep the default value.

Domain of public site  [hypha.test]:
Domain of apply site  [apply.hypha.test]:
Superadmin Email  [superadmin@hypha.test]:
Superadmin Password  [hypha123]:
Site port [8090]:
>>> Created superuser with email superadmin@hypha.test.
>>> Set public site to hypha.test:8090
>>> Set apply site to apply.hypha.test:8090
```