Add silent-on-success option to Kustomize build

[ifutivic]

Following the blog post from Steven Engelhardt and the Aspect rules_js rules, I wanted to add an option for successful builds to be silent.

Our YAML files contain many commonLabels and patchesStrategicMerge entries, which build successfully but generate excessive warnings to stderr. We're migrating away from these patterns, but in the meantime, they flood our CI logs and obscure other important output. Kustomize doesn't offer a built-in way to suppress these.

This PR adds a silent_on_success attribute to the kustomize_resources rule. It redirects stderr to a temporary file and only displays it if the command fails (non-zero exit code).

Happy to make this false by default instead 😄

[ifutivic]

@seh Please take a look at this after the holidays 😄

We really love this ruleset and would prefer not to patch or fork it to keep this option.