Improve the error message when Knative is not installed
Description
Following error message gets displayed when Knative is not installed:
Creating service: services.serving.knative.dev is forbidden: User "system:serviceaccount:gitlabktl-11080193:gitlabktl- 1080193-service-account" cannot create resource "services" in API group "serving.knative.dev" in the namespace "gitlabktl- 11080193"
Job #220627290 failed for 726ab893:
Proposal
Check if Knative is installed and show an error that is easier to understand.
Edited by Grzegorz Bizon