Summary

Part of #3073

This PR adds a new API to the Node.js called applyConfiguration, which allows a user to apply their own configuration when using the APIs. In this PR, only formatContent is covered.

This won't be the only way a user can offer custom configuration, but it sets the foundation to allow to do so.

The reason why I chose to have a separate function was purely cosmetic. Some option I can see:

1. Create a new static method called Rome.createWithConfiguration(configuration, backendOption), where configuration is mandatory
2. Add a new parameter to Rome.create(options, configuration). Although it would lower down the usability because it would unlock something like this Rome.create(undefined, {}), which I don't like to be honest 😛

While doing so, I realised two things:

• the name of properties passed to applySettings inside the Workspace where in snake case
• the shape of the object did not reflect the shape of rome.json

This is caused by the fact that the configuration inside rome.json and the configuration inside the Worskpace are different. This is OK, because rome.json needs to offer a more user-friendly shape, while the workspace needs to contain a configuration that suits us developers.

In this PR I made the following changes to the configuration:

• the function apply_settings inside the server.rs now accepts a Configuration object, which is the user configuration, and it gets mapped using the function merge_with_configuration, which is a function that we already use. This has the effect that now the playground you can see a different shape in the configuration: it's exactly like the rome.json and their properties are in camelCase; I believe it's a great improvement!
• I added comments to the auto-generated workspace.ts files; this is merely a user experience goody, but it felt weird that we offer a JSON schema in VSCode for our rome.json file, but we don't offer documentation for our configuration in the runtime; the formatted result of the generated code is awful, because our formatter doesn't format comments and get the correct indention is basically impossible. This should not be a show-stopper;

Test Plan

I created a new test