message: (fix) - export `formatDocument`
  When trying out the graphCache exchange I noticed we were missing the formatDocument helper that is used inside that package.
diff: @@ -4,4 +4,4 @@ export * from './components';
  export * from './exchanges';
  export * from './hooks';
  export * from './types';
  -export { CombinedError, createRequest } from './utils';
  +export { CombinedError, createRequest, formatDocument } from './utils';
  