We're seeing odd failures with Prettier on some CI branches; my hunch is that they are installing different versions of the package and therefore getting formatting conflicts. This PR updates them all and pins them to specific versions - something we should probably consider generally, or remove our `package-lock.json` from the gitignore.
This commit adds a new built-in handler for querying by accessible name and role (#6307).
Support for waitForSelector will be added in a follow-up commit.
