Add a domain to a company. Rejected if the domain already belongs to another company (naming it) or is a free-mail provider. Triggers the async domain auto-association job.

Request body to add or remove a domain on a Company.

Result of a domain add/remove operation, including how many profiles were affected so the caller can report it (e.g. the FE's company_domain_added/company_domain_removed Mixpanel events).