Fix`set-version` to also update `packages/react-native` source (#42897)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/42897

Changelog: [Internal] - Update nightly flow to use set-version

This change fixes `set-version` to update the `packages/react-native` native source and build files (as `set-rn-version` does) -- this was an oversight but not an issue as `set-version` isn't actually used anywhere right now.

Reviewed By: huntie

Differential Revision: D53463414

fbshipit-source-id: d0d9e4bbe246cccb8643a6ebf9794122bc343433