Verify recursive type definition

[dansanduleac]

This is to test that clients can successfully handle such definitions at runtime.

Aimed to ensure that this fix will work for python: palantir/conjure-python#9.

Example:

types:
  definitions:
    default-package: whatever
    objects:
      ZigOrZag:
        union:
          zig: Zig
          zag: Zag
      Zig:
        object:
          recursive: ZigOrZag
      Zag:
        alias: string

(and an endpoint that references ZigOrZag)

[dansanduleac]

Outside the scope of this project as it tests generation rather than wire format, and it also complicates parsing.