Creates a new partner organization with a name and a partnershipExternalId (your own id for the partner, used to refer to it in your systems), and immediately sets up an active partnership and routing availability so the new organization can send jobs to your organization (it will then appear in GET /v1/partners). ONLY use this endpoint if you know the partner is not already on the platform — creating a duplicate organization for a partner that already exists will fragment their data. Use GET /v1/partners first to check whether the partner already exists.