[IBCDPE-1004] Implement Postgres server

[BryanFauble]

TODO: Clean up the branch before marking the PR for ready for review. I had deployed out a testing stack in spacelift.

Problem:

1. Airflow did not recommend using the airflow instance from their helm chart for a production load due to the maintenance requirements of handling it.

Solution:

1. Implementing https://cloudnative-pg.io/documentation/current/
2. Updating the connections for airflow to use the new connection and set up the account secrets automatically.

Description of tool:

CloudNativePG is an open source operator designed to manage PostgreSQL workloads on any supported Kubernetes cluster. It defines a new Kubernetes resource called Cluster representing a PostgreSQL cluster made up of a single primary and an optional number of replicas that co-exist in a chosen Kubernetes namespace for High Availability and offloading of read-only queries.

Applications that reside in the same Kubernetes cluster can access the PostgreSQL database using a service which is solely managed by the operator, without having to worry about changes of the primary role following a failover or a switchover.

Testing:

1. Verified that a deployment of the operator and cluster for airflow worked, airflow came up healthy. I was able to log in, and trigger a DAG.

[BryanFauble]

Will open this back up shortly