printer package Print does not print descriptions

[mmmveggies]

Hello,

First of all, thank you to everyone involved in writing this package! I have used it extensively and started publishing some helpers at https://github.com/Fanatics/graphql-ast-helpers

One thing I'm confused about - calling printer.Print doesn't seem to emit the descriptions in the standard triple-quoted style, though the parser seems to have tests to ensure it can detect them ... am I just missing something, or would the printer need to be extended to support this?

I would be happy to look at it if it's currently unsupported or not planned, though I'm not quite familiar with the visitor pattern and a nudge in the right direction would probably save me a lot of time.

My guess would be:

1. Each member function of the printDocASTReducer that can have a description prefix may need to try to read that value, and then fields that do have a description need to have that value be indented + newline'd (to support multiline comments) correctly in the output string
2. Some places like ast.FieldDefinition.InputValueDefinition the may have to conditionally newline when they are currently always inline, to support something like the following

"""cool type"""
type Cool {

  """every cool bean"""
  beans: [ID]

  """
  check if a cool bean is present
  the resolver for this is super optimized
  """
  hasBean(

    """the id of the cool bean"""
    id: ID = "abc123"
  ): Boolean
}

Cheers!