Support configuring multiple namespace for multiNamespaceMode

[hussein-awala]

This PR adds a new value, airflowNamespaces to create some resources usually used by the K8S worker/K8S pod when creating them in another namespace.

I'm trying to refactorize the method:

{{- $workersNamespaces := list }}
{{- if .Values.multiNamespaceMode }}
  {{- range $namespace := .Values.airflowNamespaces }}
    {{- $workersNamespaces = mustAppend $workersNamespaces ($namespace | quote) }}
  {{- end }}
{{- end }}
{{- if not (has (.Release.Namespace | quote) $workersNamespaces) }}
    {{ $workersNamespaces = mustPrepend $workersNamespaces (.Release.Namespace | quote) }}
{{- end }}

and move it to _helpers, but I have a problem with the returned value (string), which is badly parsed in the templates.

[shohamy7]

Hi! @hussein-awala
I am interested in this PR, so I will try to help :)
I encountered the problem with returning list from define in the past, it seems like it's not possible as define helpers only returns strings.
Maybe you can workaround this issue by converting the list to and from json as suggested in the following SO issue: https://stackoverflow.com/questions/77438391/return-a-list-variable-from-a-helm-helper-function
It seems a bit hacky but it does the trick.
Let me know what you think!

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[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.