Apply the default Grafana Version to the CR spec

[theSuess]

Currently, the default Grafana version, is transparently used to create the instance if no custom image is specified.

When we update the default version in the operator, this will lead to unexpected Grafana upgrades.

To remedy this, we should add a field to control the version used by the operator. For example:

apiVersion: grafana.integreatly.org/v1beta1
kind: Grafana
metadata:
  name: grafana
  labels:
    dashboards: "grafana"
spec:
  version: '10.4'

The version would correspond to the container image tag.

If this field is not set in the applied spec, the operator should set it for the user. By explicitly applying the default version, the version is locked and will not be unexpectedly upgraded due to the operator changing the default version

[theSuess]

Another option would be to add a field to specify the image used and set this if empty.

One example of another operator doing this is the MinIO operator: https://github.com/minio/operator/blob/798825dd0a9071875e89f0af321dc671a4e995f8/api/tenant_update.go#L52

[pb82]

@theSuess I wonder, why set the version in the spec and not the status?

[theSuess]

Setting the version in the spec allows us to pin the version in the resource, that way operator updates will not result in an unplanned upgrade of Grafana