Replace lerna and yarn with npm workspaces

[janechu]

Pull Request

📖 Description

This change replaces yarn and lerna with npm workspaces. This should help a lot with dependency management as we were on yarn 1 which had a fairly heavily manipulated dependency tree.

The changes also upgrade most dependencies to their latest versions and the changes may reflect this, such as updating all versions of webpack to webpack 5.

✅ Checklist

General

• [x] I have included a change request file using $ yarn change
• [ ] I have added tests for my changes.
• [x] I have tested my changes.
• [ ] I have updated the project documentation to reflect my changes.
• [x] I have read the CONTRIBUTING documentation and followed the standards for this project.