💡 Allow converting "configuration hints" into errors

[lishaduck]

Suggest an idea for Knip

When a package is in ignoreDependencies but then gets used, Knip gives off a configuration hint. They're useful, but only if you notice them. I primarily run checks in CI, so if it doesn't error, I don't see it. I'd love to convert these issues into errors, forcing me to remove them so that the config stays clean and up-to-date.
Given that hints exist, all of the logic is probably there; this'll probably just need to wired up to however you manage exit codes.