Support k8s helm secrets creation for logstash helm chart

Describe the feature: For convenient use of k8s secrets should add helm chart for create secrets.

Describe a specific use case for the feature: Add secrets for using in k8s should be more convenient from the one logstash helm chart.

The helm chart for secret can looks like bellow

secret.yaml

{{- if .Values.logstashSecrets }}
{{- range .Values.logstashSecrets }}
---
apiVersion: v1
kind: Secret
metadata:
name: {{ template "logstash.fullname" $ }}-{{ .name }}
labels:
  app: "{{ template "logstash.fullname" $ }}"
  chart: "{{ $.Chart.Name }}"
  heritage: {{ $.Release.Service | quote }}
  release: {{ $.Release.Name | quote }}
  {{- range $key, $value := $.Values.labels }}
  {{ $key }}: {{ $value | quote }}
  {{- end }}
data:
{{- range $key, $val := .value }}
{{ $key }}: {{ $val | toString | b64enc | quote }}
{{- end }}
type: Opaque
{{- end }}
{{- end }}

values.yaml

logstashSecrets:
  - name: "env"
    value:
      logstash.conf: |
          input {
            exec {
              command => "uptime"
              interval => 30
            }
          }
          output { stdout { } }
      api_key: ui2CsdUadTiBasRJRkl9tvNnw
  - name: "tls"
    value:
      ca.crt: "LS0tLS1CRUdJT0K"
      cert.crt: "LS0tLS1CRUdJTiBlRJRklDQVRFLS0tLS0K"
      cert.key: "LS0tLS1CRUdJTiBgUFJJVkFURSBLRVktLS0tLQo="

[kksudo]

Yes, it’s easy. I’ll be doing PR soon.

[jmlrt]

Done in #712