Add annotations to frontend helm template. (#6163)

This is similar to annotations in backend template at
https://github.com/tidaltech/cvat/blob/develop/helm-chart/templates/cvat_backend/service.yml#L10-L13

helm-chart/templates/cvat_frontend/service.yml

@@ -7,6 +7,10 @@ metadata:
     {{- include "cvat.labels" . | nindent 4 }}
     app: cvat-app
     tier: frontend
+  annotations:
+    {{- with .Values.cvat.frontend.service.annotations }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
 spec:
   selector:
     app: cvat-app