Rename the organization

Gives the organization the name an owner chose. Owners only. Organizations created before this existed carry a name derived from whoever signed up first, and this is the only way to change one. The name is a label: the slug does not move with it, because something may already point at the slug. Idempotent by target and value, so there is no client_id. Do not build this request from the organization id — follow the rename_organization action on the workspace representation, whose name field carries the current value.