[dev]: update-vscode.sh should checkout package.json and update yarn.lock

[jsjoeio]

I think I mentioned this before but I wonder if we should modify the VS Code PR script to checkout the package.json and yarn.lock, then remove the dependencies we don't want and regenerate the lock.

— @code-asher

Relevant code: https://github.com/cdr/code-server/blob/main/ci/dev/update-vscode.sh

[code-asher]

We should also automatically move ripgrep to dependencies as part of this: #3383

[stale]

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