dedupe warning messages for deprecated API warnings

[kensipe]

It took some research to get here... many things to liggitt as well!

Fixes: #1711

Inspiration for fix from kubectl https://github.com/kubernetes/kubernetes/blob/release-1.19/pkg/kubectl/cmd/cmd.go#L433
Details https://kubernetes.io/blog/2020/09/03/warnings/

This solution will continue to print a Warning message for each interaction that involves a deprecated API for each deprecated API but that's it... any repeated use of that API will not print.

Output for a simple kudo init --dry-run after the fix:

❯ go run cmd/kubectl-kudo/main.go init --dry-run --version 2
$KUDO_HOME has been configured at /Users/kensipe/.kudo
Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
Errors
failed to detect any valid cert-manager CRDs. Make sure cert-manager is installed.
Error: failed to verify installation requirements
exit status 255

Also hard to see on GH but the word Warning: is colored yellow as well here (which it is not below)

Output for a simple kudo init --dry-run prior to fix:

❯ go run cmd/kubectl-kudo/main.go init --dry-run --version 2
$KUDO_HOME has been configured at /Users/kensipe/.kudo
W1012 16:36:39.397078   28236 warnings.go:67] apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
W1012 16:36:39.400591   28236 warnings.go:67] apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
W1012 16:36:39.404028   28236 warnings.go:67] apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
W1012 16:36:39.412952   28236 warnings.go:67] apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
W1012 16:36:39.416993   28236 warnings.go:67] apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
Errors
failed to detect any valid cert-manager CRDs. Make sure cert-manager is installed.
Error: failed to verify installation requirements
exit status 255

Signed-off-by: Ken Sipe kensipe@gmail.com

[kensipe]

also... this nicely fixes all usages

[alenkacz]

thank you 👏