fix helm lint by defining new template helper

[rajatjindal]

helmify replaces release name (in this case spin-operator) with {{ .Release.Namespace }} in dnsNames for Certificate object.

This means {{ include "spin-operator.fullname" . }} gets replaced with {{ include "{{ .Release.Namespace }}.fullname" . }}

This is most likely a bug in helmify, but we can workaround it by defining a new template helper with name {{ .Release.Namespace }}.fullname

[github-actions]

This PR now has an image available for testing:

  ttl.sh/spoopy-operator-pr-:24h

[michelleN]

Thanks @rajatjindal !

cc/ @vdice - would love your thoughts here.

[vdice]

I'm still trying to catch up w/ all of the activity while out sick, but liking the creativity here! Assuming we're still in the phase of wanting to use helmify and not yet ready to manually manage the chart, this seems like a good way to get what we need.