Sync WooCommerce Email optin to ActiveCampaign's "Has opted in to marketing"

This would allow a cleaner handling of automations based on those opt-ins on Active Campaign side. Now it can be done via a tag, but tag-based triggers in ActiveCampaign don’t fire if the contact already has the tag and the tag is applied. So you have to work around this with tags removing again etc. It would also make sense in the general philosophy of matching data with an equal purpose.