Bump Yarn to v4

[mcmire]

This is a prerequisite for adding automated publishing to this repo.

• [ ] Add scripts/prepack.sh
• [ ] Replace prepublishOnly package script with prepack
• [ ] Bump Yarn version to v4
• [ ] Replace .yarnrc with .yarnrc.yml
• [ ] Add constraints file from module template, address any divergences
• [ ] Add lint:constraints package script, integrate into lint script