[REFACTOR]: Create a state store interface compatible with Redis/ValKey etc.

[acouvreur]

The Store is where the instances are stored for future expiration by the store engine itself.

This mean that any future store implementation must have an expiration mechanism. If the underlying engine does not have one, the store will have to check the engine state on a regular basis.

The interface to implement is:

type Store interface {
	Get(context.Context, string) (instance.State, error)
	Put(context.Context, instance.State, time.Duration) error
	Delete(context.Context, string) error
	OnExpire(context.Context, func(string)) error
}

This allow user to register expiring key notification to stop the related workload on the provider.