Summary:
Fixed the test script to properly setup our third-party deps and tweaked the third-party specs a bit so they work correctly.

This currently works for projects using static libraries, but fails when using dynamic libraries (`--use-libraries`)

cc mhorowitz alloy
Closes https://github.com/facebook/react-native/pull/14100

Differential Revision: D5380728

Pulled By: javache

fbshipit-source-id: e78b6bd4466ebf2bf30b7e361eff10ec14b36a55