Allow a `iri-<kind>` runtime to expose events on its own

[adracus]

Summary

Currently, to listen to events of an ori-<kind> runtime, we continuously List and infer events using the ori event generator. This works good enough, however it is not optimal. We should extend the various ori interfaces to allow a runtime below to expose its events directly (e.g. the machinebroker could expose the watch events) and consume these instead of inferred ones.