Infra services should be deployable separately

Problem

It's not possible to deploy a single infrastructure service: ingress-nginx, cert-manager, mongodb, keycloak, minio, postgresql.

Solution

Add infra subcommand to build and deploy commands.

Don't forget

• Adapt build and deploy commands
• Adapt gitlab CI
• Backup/restore (keycloak, mongodb, minio) : all in the same directory ?