refactor(examples/react/{nextjs-app-optimistic-updates,nextjs-app-prefetching}): move the data layer into 'services/{domain}' with a query factory

An automatically generated fix could have been available for this error, but the fix-ci step hasn't completed. Ensure it's configured to always run in your CI pipeline to get automatic fixes in future runs. For more information, see the Self-Healing CI docs.