Changes to Update Course Structure

added the new excellence_course enum value to the source_type/anyOf[subschema #1] response property for the response status 200

added the new interactive enum value to the units/anyOf[subschema #1]/items/blocks/anyOf[subschema #1]/items/type response property for the response status 200

added the new video enum value to the units/anyOf[subschema #1]/items/blocks/anyOf[subschema #1]/items/type response property for the response status 200

added the new interactive enum value to the request property units/items/blocks/anyOf[subschema #1]/items/type

added the new video enum value to the request property units/items/blocks/anyOf[subschema #1]/items/type

added the optional property append_error_message to the response with the 200 status

added the optional property append_started_at to the response with the 200 status

added the optional property append_status to the response with the 200 status

added the optional property excellence_content_signature to the response with the 200 status

added the optional property excellence_course_key to the response with the 200 status

added the optional property excellence_unmodified to the response with the 200 status

added the new optional request property units/items/blocks

added the optional property units/anyOf[subschema #1]/items/blocks to the response with the 200 status