feat: pnpm

[tyrauber]

Remove yarn / pnp, in favor of pnpm.

✅ $ pnpm unittest ✅ $ pnpm test:plugin ✅ $ pnpm build:plugin ✅ $ pnpm generate 🚩 $ pnpm lint

Checklist

• [ ] I have tested this on a device/simulator for each compatible OS
• [ ] I formatted JS and TS files with running yarn lint:fix in the root folder
• [X] I have run tests via yarn test in the root folder
• [X] I updated the documentation with running yarn generate in the root folder
• [ ] I mentioned this change in CHANGELOG.md
• [ ] I updated the typings files (index.d.ts)
• [ ] I added/updated a sample (/example)