ODRC: Create Helm charts

[sergei-maertens]

The application needs to be deployed using Helm, so we require the relevant charts.

Tasks

• Create Helm chart for registration component (this repository). It's a standard Maykin Django project, with:
  • OIDC login for admin
  • No celery (no worker, flower, beat)
  • Redis is used for cache
  • PostgreSQL database
  • Available environment variables are documented. Some are unused: SITE_ID, CSRF_TRUSTED_ORIGINS, NOTIFICATIONS_DISABLED, DISABLE_2FA (not sure about this, either way, it should not be disabled): Registratie component helm chart maykinmedia/charts#141
• Create chart for OPDC: ODPC chart maykinmedia/charts#143
• Create an Umbrella chart - the registration component needs an Open Zaak instance (or other Documents API implementation). It should be configurable to use an existing instance, or deploy a fresh, isolated Open Zaak instance.