This is much more flexible than `monaco-plugin-helpers`. Because of
this, it’s possible to use Prettier as an external dependency, so users
can ignore it in their own build process of they choose not to support
formatting.
Instead of rewriting YAML language service imports in the build tool, I
decided to just import them from where they need to be imported in the
source code.
Closes#63
Most notably update to Webpack 5. Webpack 5 supports web workers without
the need of a loader, so the `webpack-worker-loader` example has been
removed.
Npm 7 also supports workspaces, but doesn’t require the workspace root to be
private. This means the examples can be workspaces within the project, so the
entire project can be handled as one mono repository with a single lock file and
`node_modules` directory.
Also the readme has been updated with usage instructions.
