misc: helm sideload initContainer option (#4325)

***NO_CI***

dev/helm/templates/deployment.yaml

@@ -21,6 +21,16 @@ spec:
       serviceAccountName: {{ include "wiki.serviceAccountName" . }}
       securityContext:
         {{- toYaml .Values.podSecurityContext | nindent 8 }}
+      {{- if .Values.sideload.enabled }}
+      initContainers:
+        - name: {{ .Chart.Name }}-sideload
+          image: "{{ .Values.image.repository }}:{{ default "latest" .Values.image.tag }}"
+          imagePullPolicy: {{ default "IfNotPresent" .Values.image.imagePullPolicy }}
+          env:
+            {{- toYaml .Values.sideload.env | nindent 12 }}
+          command: [ "sh", "-c" ]
+          args: [ "mkdir -p /wiki/data/sideload && git clone --depth=1 {{ .Values.sideload.repoURL }} /wiki/data/sideload/" ]
+      {{- end }}
       containers:
         - name: {{ .Chart.Name }}
           securityContext: