Create domain exclusions

Add domains to the exclusion list. Domains are saved without the scheme, www., port or path, so https://www.example.com/about is saved as example.com. Returns the status of each domain sent: success when it was added, duplicated when it was already on the list, and error when it isn't a valid domain, such as an email address. A domain only excluded by a CRM sync is added alongside that entry and returns success.