Watch secrets linked to a MedusaConfiguration to trigger reconciles

[adejanovski]

Secrets referenced in a MedusaConfiguration object should be watched by the MedusaConfiguration controller in order to update their status if a secret was deleted.

Such secrets need to have an owner reference set to the MedusaConfiguration object during the reconcile, which will then be used in the watcher handler.
One of the outcomes is that such a secret can be referenced by a single MedusaConfiguration. Any attempt to create a MedusaConfiguration object which tries to reference an already referenced secret should fail the reconcile and set the ControlStatusSecretAvailable condition to false with the appropriate message.

Definition of Done

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1. An owner reference is placed on secrets referenced by a MedusaConfiguration resource
2. Trying to reference a secret that's already owned by another MedusaConfiguration should fail the reconcile
3. The MedusaConfiguration controller watches secrets which are owned by a MedusaConfiguration resource, similar to what the ReplicatedSecret controller does

[adejanovski]

Replaced by #1253