Experiment: Added support for node-based debugging

[zesterer]

This PR adds experimental support for walking parse trees to extract information about them. The resulting node graph can be used to generate both EBNF for arbitrary chumsky parsers, or railroad diagrams.

For example, here is the EBNF for the example Brainfuck parser.

def_1 ::= { '<'
  | '>'
  | '+'
  | '-'
  | ','
  | '.'
  | ('[' def_1) ']' };

def_1

And here is the railroad diagram for the example JSON parser.