Change certificates to include namespace-specific SANs
This applies to all certificates apply from the namespace used by the knative-serving servers and ingress gateways
Ensure the same certificate can be used for both clients and servers in support of mTLS
@davidhadas: The label(s) area/networking cannot be applied, because the repository doesn't have them.
In response to [this](https://github.com/knative-sandbox/control-protocol/issues/264):
>1. Change certificates to include namespace specific SANs
>This applies for all certificates apply from the namespace used by the knative-serving servers and ingress gateways
>
>2. Check if we create ingress a certificate for the ingress namespace and if not create it.
>
>/area networking
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Change certificates to include namespace-specific SANs This applies to all certificates apply from the namespace used by the knative-serving servers and ingress gateways Ensure the same certificate can be used for both clients and servers in support of mTLS