Refactoring non-s-expression languages

[jackfirth]

Resyntax should be able to refactor more than just #lang racket and #lang racket/base code. For example, Resyntax should be able to rewrite this:

#lang rhombus
(1 + 2) + 3

Into this:

#lang rhombus
1 + 2 + 3

Immediate applications include writing refactoring rules specific to Rhombus, Typed Racket (see #13), and Scribble.

I have some ideas about how to get this working, but no concrete solution yet. And I don't yet know how to address the fmt side of things here.