message: change registration model to fit what is/will be implemented by
diff: @@ -3,6 +3,7 @@ import { computed } from '@ember-decorators/object';
  import { buildValidations, validator } from 'ember-cp-validations';
  import DS from 'ember-data';
  +import DraftRegistrationModel from 'ember-osf-web/models/draft-registration';
  import CommentModel from './comment';
  import ContributorModel from './contributor';
  import InstitutionModel from './institution';
  @@ -54,9 +55,7 @@ export default class RegistrationModel extends NodeModel.extend(Validations) {
  @attr('object') registeredMeta!: RegistrationMetadata;
  // Write-only attributes
  - @attr('fixstring') draftRegistration?: string;
  - @attr('fixstring') registrationChoice?: 'immediate' | 'embargo';
  - @attr('date') liftEmbargo?: Date;
  + @attr('array') includedNodeIds?: string[];
  @computed(
  'withdrawn', 'embargoed', 'public', 'pendingRegistrationApproval',
  @@ -102,6 +101,10 @@ export default class RegistrationModel extends NodeModel.extend(Validations) {
  @hasMany('institution', { inverse: 'registrations' })
  affiliatedInstitutions!: DS.PromiseManyArray<InstitutionModel> | InstitutionModel[];
  + // Write-only relationships
  + @belongsTo('draft-registration', { inverse: null })
  + draftRegistration!: DraftRegistrationModel;
  +
  registrationStateMap(): Record<RegistrationState, boolean> {
  const {
  pendingRegistrationApproval,
  