[knative] Subscription or Trigger can sink only to Kservice, but should to any Addressable

Description of problem:

Knative Subscription or Trigger CRs can address any Addressable in theirs sink section. Using the ODC UI it's only possible to address Knative services. That limits the users options.

Prerequisites (if any, like setup, operators/versions):

Install Serverless & Serving & Eventing

Steps to Reproduce

1. Follow openshift/openshift-docs#29367 to create Channel named example1 and Broker called example2.
2. Follow openshift/openshift-docs#29367 to create a Subscription from a Channel named example1 that targets a Broker called example2. Or create a Trigger from a Broker named example2 that targets a Channel called example1

Actual results:

A warning box is displayed stating that you need Knative service as a Target of subscription or Trigger.

Expected results:

It should be possible to create either of those configurations. It should also be possible to target any other addressable like regular Service or Route.

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

4.7.0-0.nightly-2021-02-04-031​352