Remaining OSS Repository Contribution and Publishing True-Ups

[ddurst-nvidia]

Moving these repositories from private to public leaves a few last-minute
changes before the transition is complete, even after the repositories are
made public.

It is not our intent to block contributions at this time. This is mostly a
matter of dotting some i's and crossing some t's on our end.

yaml-sigil-traits

• Remove private-repository CI authentication.
• Test the public fork and pull request flow.
• Test crates.io publishing automation.
  • This may involve some visible publishing churn.
• Add macOS and Windows CI.
  • Until then, CI validates Linux only.