Unsubscribe all users in a company from outbound emails

When a client leaves or is on a bespoke product, we need to stop standard client-facing emails for everyone linked to their company.

At the moment, this has to be done one person at a time. Add a company-level action that lets an admin unsubscribe all current members at once, either from all emails or selected subscriptions. Ideally, admins could also choose whether future members inherit the setting.