- remove customized external verovio module (setup-verovio, verovio-util/)
- update webpack config, yarn.lock, package.json
- use `wasm` verovio toolkit
- introduce verovio worker for development

Resolves: #1221

- Use `wasm` verovio for development (`webpack.config.js`)
- Load from verovio website for production (`webpack.pages-config.js`)
- Remove redundant `webpack.dev.config.js`

Resolves: #1219, #1221