This adds a logkey.Key for attaching the key being reconciled to a logger we embed into the context passed to Reconcile. The point of this is to enable us to eliminate [this](928d580756/pkg/reconciler/v1alpha1/service/service.go (L101-L104)) boilerplate from each of the Reconcilers.
These aren't identical, this has the form:
knative.dev/key: foo/bar
What it's replacing has the form:
knative.dev/namespace: foo
serving.knative.dev/service: bar
However, the type information present in the latter is redundant with the controller type that [should already be embedded](928d580756/pkg/reconciler/reconciler.go (L80)) in the logger.
Dave Protasowski
Matt Moore
Shashwathi
Yanwei Guo