Update gltf-pipeline files

[mramato]

Contains:

• Basic CESIUM_primitive_outline support gltf-pipeline#631
• Add base color names option gltf-pipeline#637

[cesium-concierge]

Thanks for the pull request @mramato!

• ✔️ Signed CLA found.
• ❔ CHANGES.md was not updated.
  • If this change updates the public API in any way, please add a bullet point to CHANGES.md.
• ❔ Unit tests were not updated.
  • Make sure you've updated tests to reflect your changes, added tests for any new code, and ran the code coverage tool.

Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.

[ggetz]

Thanks @mramato! Verified the changes with the relevant data linked in the PRs.