Adds support for configuring instanceAccessMode

[spatterIight]

Adds support for configuring instanceAccessMode.

This is useful for implementing logging similar to as described here: https://www.crunchydata.com/blog/log-export-examples-using-crunchy-postgres-for-kubernetes

To implement logging as described in the official article one solution is a logging pod that can mount the PVC's as read-only. To do this effectively instanceAccessMode must be "ReadWriteMany" instead of the hard-coded setting of "ReadWriteOnly".

[spatterIight]

Hmm.. this doesn't work for me the way I thought it would. When I change the mode to ReadWriteMany instead of ReadWriteOnce postgres fails to initialize:

Initializing ...
::postgres-operator: uid::26
::postgres-operator: gid::26
::postgres-operator: postgres path::/usr/pgsql-17/bin/postgres
::postgres-operator: postgres version::postgres (PostgreSQL) 17.4
::postgres-operator: config directory::/pgdata/pg17
::postgres-operator: data directory::/pgdata/pg17
install: cannot change permissions of ‘/pgdata/pg17’: No such file or directory
stat: cannot statx '/pgdata/pg17': No such file or directory
drwxr-xr-x    0    0 /pgdata

I am using Openstack Cinder as my CSI, no clue as to why simply changing the access mode would cause this...

[spatterIight]

Ended up solving this a different way. Ended up using Ansible to inject a sidecar into the statefulset as a seperate role independent from this helm chart. The sidecar harvests and sends the logs to stdout.