Ability to Purge Orphaned Products

Syncing only updates or imports products, it's not aware of deletions. Currently the only way products get deleted are through webhooks or from a complete re-import of all products. If an admin adds extra fields, or customizes the product in any way, there's no way for them to remove deletions without deleting all products and re-importing. Let's create a batch to find and purge orphaned products/variants on demand.