Add support for analyzing undeclared/unused custom properties #553
Description
Make sure to export that function as well, because we can reuse it in https://github.com/projectwallace/stylelint-plugin/blob/main/src/utils/custom-properties.ts and https://github.com/projectwallace/projectwallace.com/blob/main/src/lib/components/custom-property-inspector/analyze-custom-properties.ts
Maybe it would make sense to immediately do the same for all of these:
- custom properties
- container names
- layer names