Add NuGet.org publishing to release workflow

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• add release workflow inputs to opt into NuGet.org publishing and dry-run NuGet pushes
• add a NuGet publishing job using NuGet trusted publishing via NuGet/login@v1 and NUGET_BOT_USERNAME
• document the new release inputs and package expectations

Validation

• cargo fmt --all --check
• cargo clippy --workspace --all-targets