Fix spurious detection of yarn

[rotu]

Fixes #170101
Partial #193001

Previously, vscode could use find-yarn-workspace-root to identify that a package is using yarn as its package manager by looking for a package.json with the workspaces key. That is incorrect - npm and bun also use this key in their package manifest.

Now when running scripts from package.json in a multi-workspace package, it should default to npm. It should still use yarn if a yarn.lock file is detected.

[rotu]

@meganrogge Please let me know if you'd like me to update and/or rebase this branch for your review.

[rotu]

@meganrogge What's the next step here? It seems like the workflows have been stalled out for 10 days.

[evelant]

This is quite frustrating. I use bun in a monorepo but can't run any of my scripts as build tasks in vscode because it keeps trying to use yarn or pnpm despite having packageManager specified to bun in package.json.