Investigate possibility of refreshing secrets on rotation

[riccardomc]

Describe the solution you'd like
The ability to define a period after which the secrets with have to be rotated. Reconciliation will have to be triggered and new values pulled.

What is the added value?
Secret values are kept up to date in the cluster.

Give us examples of the outcome

Support for the new refreshInterval field.

apiVersion: external-secrets.k8s.io/v1alpha1
kind: ExternalSecret
metadata: {...}
spec:
  # the amount of time before the values will be read again from the store
  # may be set to zero to fetch and create it once
  refreshInterval: "1h"

Observations (Constraints, Context, etc):

Operator SDK already has a default reconciliation interval time of 10h.

[ecout]

+1000.

This is the ONLY reason I'm looking at solutions to leverage Secrets Manager. The ability to update configs outside of the K8s cluster.

[knelasevero]

Also would push us i the new CRD direction external-secrets/kubernetes-external-secrets#477, and I also think it is just a good feature to have.