Team accounts: invite people to one account, with roles and an audit log

An account can now have several people, admins and members, with an audit log of changes. Everyone signs in once more after this release.

• An admin can invite people by email. An invitation lasts 7 days and works once. Teams are free on every plan, with no seat limit.
• Members manage keys and data and read usage, but not billing, settings, invitations, roles or the audit log. Those are for admins.
• The audit log records who changed keys, plans, settings, data and webhooks, and cannot be edited or deleted.

AvailabilityNot live yet. It ships with the next gateway deploy.