message: mark ephemeral-checkpoint and ephemeral-store as built-in types
  Meaning they aren't something that should be offered to end users
diff: @@ -39,12 +39,18 @@ class Updater {
  {
  type: 'content-types',
  id: 'ephemeral-checkpoints',
  + attributes: {
  + 'is-built-in': true
  + },
  relationships: {
  'data-source': { data: { type: 'data-sources', id: this.dataSourceId } }
  }
  },
  { type: 'content-types',
  id: 'ephemeral-restores',
  + attributes: {
  + 'is-built-in': true
  + },
  relationships: {
  'data-source': { data: { type: 'data-sources', id: this.dataSourceId } },
  fields: {
  