Changes to GET `/api/v0/main-frontend/credit-registrations/my/enrolment-banners/by-course/{course_id}` - The caller's registrations on one course that owe them the in-course re-enrol banner. Scoped to the course rather than filtered from `/my` on the client, because every course-material page view calls this. Empty is the normal answer.

added the required property items/linking_email/oneOf[#/components/schemas/LinkingEmailStatus]/link_state to the response with the 200 status

added the required property items/is_processing_in_sisu to the response with the 200 status

added the new grade_scale_mismatch enum value to the items/error_code/oneOf[#/components/schemas/CreditRegistrationErrorCode] response property for the response status 200

added the new not_registered enum value to the items/error_code/oneOf[#/components/schemas/CreditRegistrationErrorCode] response property for the response status 200

added the new service_temporarily_unavailable enum value to the items/error_code/oneOf[#/components/schemas/CreditRegistrationErrorCode] response property for the response status 200

added the new waiting_for_course_setup enum value to the items/student_facing_status response property for the response status 200

removed the acceptor_not_found enum value from the items/error_code/oneOf[#/components/schemas/CreditRegistrationErrorCode] response property for the response status 200

removed the sisu_temporarily_unavailable enum value from the items/error_code/oneOf[#/components/schemas/CreditRegistrationErrorCode] response property for the response status 200

added the new looking_for_enrolment enum value to the items/student_facing_status response property for the response status 200

added the new sending enum value to the items/student_facing_status response property for the response status 200

added the optional property items/enrolment_checked_at to the response with the 200 status

added the optional property items/student_number to the response with the 200 status

added the optional property items/submitted_at to the response with the 200 status

removed the in_progress enum value from the items/student_facing_status response property for the response status 200

added the required property items/enrolment_found to the response with the 200 status

removed the required property items/consent_withdrawn_while_in_flight from the response with the 200 status

removed the needs_consent enum value from the items/student_facing_status response property for the response status 200

endpoint added