WildFly discovery subsystem registers capabilities using an ambiguous contract

The discovery subsystem registers capabilities of the form RuntimeCapability<Void> with a service type of DiscoveryProvider.class with the model.

However, during runtime it registers capabilities of the form RuntimeCapability<DiscoveryProvider> with the OperationContext using the same name.

This violates the capability contract. Since the capability specified during resource registration is what defines the contract, and since non-trivial discovery provider implementations cannot reasonably register an implementation during the model phase without requiring runtime dependencies, we should prefer the former definition over the latter.