External event recorder should adhere to EventRecorder interface

[hiddeco]

The Kubernetes core has the following record.EventRecorder interface:

// EventRecorder knows how to record events on behalf of an EventSource.
type EventRecorder interface {
	// Event constructs an event from the given information and puts it in the queue for sending.
	// 'object' is the object this event is about. Event will make a reference-- or you may also
	// pass a reference to the object directly.
	// 'type' of this event, and can be one of Normal, Warning. New types could be added in future
	// 'reason' is the reason this event is generated. 'reason' should be short and unique; it
	// should be in UpperCamelCase format (starting with a capital letter). "reason" will be used
	// to automate handling of events, so imagine people writing switch statements to handle them.
	// You want to make that easy.
	// 'message' is intended to be human readable.
	//
	// The resulting event will be created in the same namespace as the reference object.
	Event(object runtime.Object, eventtype, reason, message string)

	// Eventf is just like Event, but with Sprintf for the message field.
	Eventf(object runtime.Object, eventtype, reason, messageFmt string, args ...interface{})

	// AnnotatedEventf is just like eventf, but with annotations attached
	AnnotatedEventf(object runtime.Object, annotations map[string]string, eventtype, reason, messageFmt string, args ...interface{})
}

As this interface includes everything we need, including adding "metadata" using AnnotatedEventf, it would likely be better if our own event.Recorder would adhere to the above interface.

As a second step, the controllers.Events helper could be refactored into a "DelegatingRecorder" which delegates events to all underlying recorder implementations.