Update and persist `Reconciliation` status condition to reflect progress

[stefanprodan]

The Reconciliation status condition should be set to True and its message should be updated in etcd every time we observe a drift to:

• resource generation (metadata.generation != status.observedGeneration)
• reconcileAt annotation (metadata.annotations.reconcileAt != status.lastHandledReconcileAt)
• upstream revision (revision != status.artifact.revision)

In addition, when drift is detected, we should set Read=Unknown and update its message with the Reconciliation one.

If the reconciliation resulted in an error that will be retried, we should set the Reconciliation reason to ProgressingWithRetry.