feat: Improve on-prem install, documentation and compatibility k8s 1.28

[etaques]

This PR changes:

• Improving install steps on readme - completed
• added certificate required to add TLS - completed
• Fixed postgres liveness and readiness probes, was bugging default postgres user on password generation at first run - completed
• Setting default keto dsn (the postgresql connection string) as kubernetes secret and with name orb-keto-dsn as described on install steps - completed
• Adding support for traefik as IngressController using IngressRoutes, but still default nginx, only to add flexibility on-prem clusters - completed
• Adding support to nginx-internal Service as LoadBalancer, but still default ClusterIP, only to add flexibility on-prem clusters - completed
• compatibility with kubernetes 1.28 - (WIP)