Use pyhocon CLI as a formatter

I was looking for an auto-formatter for HOCON files, similar to black/ruff for python files.

I thought I would give it a go:
```bash
pyhocon -f hocon -n 4 -i app.conf -o app.conf
```

And it sort of works. The only problem is that it strips away any comments and resolved all variable substitutions.

Will it be possible to support an option to just format the file, without also resolving it?