code_builder import from GitHub.

The big change affecting all of the goldens is that we now add trailing commas.
The motivation is that code with trailing commas can avoid pathological corners
of the formatter, which can save entire seconds in generating some Dart source
code.

See details at: dart-archive/code_builder#376

  - f635ab6e2776955d057cf75757905f73f76adbd9 Add support for trailing commas in Emitter (#376) by Sam Rawlins <srawlins@google.com>
  - e082adb3e01d619370e7ec14b5f8ae6ac8ecf903 Fix spelling in README.md (#360) by Saint Gabriel <53136855+chineduG@users.noreply.github.com>
  - bed3ca90fb5a42b2b4c7fc93a8d73652a06d4314 Fix spelling in CHANGELOG.md (#361) by Saint Gabriel <53136855+chineduG@users.noreply.github.com>

PiperOrigin-RevId: 469597645

Author: srawlins