Support for certificate authentication for the event router

Q) Proposed title of this feature request
A) Add support for certificate authentication for the event router when using kafka sink.

Q) What is the nature and description of the request?
A) We want to be able to filter Openshift events on a kafka topic, rather than on stdout. The event router already supports kafka topics, but the only authentication method currently implemented are username/password, which is configured in a config map. To increase security we would like to be able to use certificate validation in stead and have this configuration put in a secret instead.

Q) Why does the customer need this? (List the business requirements here)
A) We're already using a large event driven platform on Kafka and needs both an official support for Kafka sinks on the event router, including the increased security around certificate authentication.

Q) List any affected packages or components.
A) The Openshift event router