chore(0.81): new patch release

[Saadnajmi]

Summary

• Add an Nx version plan for a new 0.81 patch release
• Prepare the stable branch for nx release to bump react-native-macos and @react-native-macos/virtualized-lists from 0.81.7 to 0.81.8

Changes since v0.81.7

• feat(0.81, ci): prebuild React xcframework for macOS (feat(0.81, ci): prebuild React xcframework for macOS #2921)
• chore(0.81, deps): Bump various packages to mitigate CVEs (chore(0.81, deps): Bump various packages to mitigate CVEs. #2931)
• fix(0.81, ci): use mapped upstream version for Hermes version marker (fix(0.81, ci): use mapped upstream version for Hermes version marker #2934)

Validation

• yarn nx release --dry-run --verbose --skip-publish

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