Improve JsLIGO's formatter
We'd like to improve the pretty printer for JsLIGO in order to aid with transpilation and also to improve the output of capabilities like hover in the language server.
Beauty is subjective, so let's base ourselves on something like https://prettier.io/ to have something that feels familiar to TypeScript developers.
Acceptance criteria
- We've improved the JsLIGO's formatter to have a reasonable output.
- Tests added.