Add an opinionated formatter

[obycode]

It is always useful to have a formatter to fix whitespace and other minor formatting changes in your code. Our VSCode extension should provide a formatter for Clarity files.

[obycode]

I believe the main missing component needed to implement this would be maintaining the comments in the AST. There is currently no data structure to hold comments, so they are treated the same as whitespace in the code. If we add a new PreSymbolicExpressionType for comments, then it should be relatively easy to implement a formatter.

[lgalabru]

Related https://github.com/hirosystems/clarinet/pull/664

[smcclellan]

@hugocaillard to add more detail here.

[smcclellan]

Update: This will be started either later this quarter (Q3) or start of next.