Add debugDescription api for Apollo generated types

[raymondk-nf]

Use case

Given any schema, the code generated by Apollo allows for elegant use of those strong types within Swift code. When debugging though, it's another story. Currently, developers are forced to po individual value type fields and cannot print top level objects to the debug console.

type Book {
  summary: Summary
}

type Summary {
  title: String
}

Here if you po on a book's summary, you get a DataDict

(lldb) po book.summary
▿ Optional<Summary>
  ▿ some : Summary
    ▿ __data : DataDict
      ▿ _storage : <_Storage: 0x3036f1f80>

Developers are forced to print out values for value types only.

(lldb) po book.summary.title
▿ Optional<String>
  - some : "My Book"

Describe the solution you'd like

Feature request here is to add a debugDescription to any code generated type from provided schema to allow for debugging capabilities.