LSP Request: Implement range formatting, fix formatting of dirty files

We want to implement various LSP requests that were present in the old language server in the new language server. Also, formatting erase the latest changes in case the file was dirty, which should be not hard to fix after we can print the CST without parsing it from a file.

Acceptance criteria

• We implement range formatting from the LSP specification.
• Formatting works correctly with dirty files
• Tests are added showing it works.