Support feature flags through KnativeServing CRD in the Operator

[kromanow94]

Problem
It would be nice if the knative feature flags could be configurable through the KnativeServing CRD.

https://knative.dev/docs/serving/configuration/feature-flags/

Persona:
System Operator

Exit Criteria
Feature flags can be configured by the Operator for knative serving through the KnativeServing CRD.

[houshengbo]

@kromanow94 Do you mean to configure the config-features ConfigMap?
The operator is able to configure any ConfigMap available with knative serving and eventing: https://knative.dev/docs/install/operator/configuring-with-operator/#configuring-knative-by-using-the-operator

[kromanow94]

Maybe the config-features config map is supported by the operator through code but not in the CRD? I wasn't able to find the features: section in the CRDs:

• config/crd/bases/operator.knative.dev_knativeservings.yaml
• config/charts/knative-operator/templates/operator.yaml