linter: Validate OpenShift objects

[avisiedo]

• Add the ./devel/check-k8s.sh script for validating the k8s objects generated by kustomize.
• Add integration of the above script in lint.sh script.
• Document the script at DEVOPS.md file.
• The validation will be launched on the scenarios below:
  • When running ./devel/check-k8s.sh.
  • When running ./devel/lint.sh and we are logged in a cluster or provide the environment variables with the credentials.
  • When the pre-commit git hook is executed (if it was set-up), as it calls internally to ./devel/lint.sh.
  • When the pipeline execute ./devel/lint.sh and the credentials to log in to the cluster exists.

[frasertweedale]

@avisiedo this PR now has conflicts (for real) as a result of other merges.