Approves a PENDING join request and creates the requester's User in your account's default team. Set role to ROLE_READ_ONLY, ROLE_ORG_ADMIN or ROLE_TENANT_ADMIN. If you leave role out, the person gets ROLE_READ_ONLY, the least access. The person is emailed that they were approved. Returns 409 if the request was already decided and 422 if it has expired. Callable by an Account Administrator (ROLE_TENANT_ADMIN) or a Team Administrator (ROLE_ORG_ADMIN). A Team Administrator can grant ROLE_READ_ONLY or ROLE_ORG_ADMIN. Only an Account Administrator of this account, or a platform administrator, can grant ROLE_TENANT_ADMIN.