Add openHalo as a PostgreSQL flavor

openHalo provides the capability for PostgreSQL to work with applications written for MySQL but provides much more better performance than MySQL!

Repository: https://github.com/HaloTech-Co-Ltd/openHalo

License: GPLv3

Implementation proposal

Create a new PostgreSQL flavor called openhalo in order to support openHalo:

apiVersion: stackgres.io/v1
kind: SGCluster
spec:
  postgres:
    flavor: openhalo
    version: "14.18"