[Loki-Distributed] Add extraObjects: [] to values

[BestChinchilla]

It would be convenient to add third-party manifests.

Something like this:

{{- range .Values.extraObjects }}
---
{{- if kindIs "map" . }}
{{ tpl (toYaml .) $ }}
{{- else }}
{{ tpl . $ }}
{{- end }}
{{- end }}