Summary:
In order for `CxxModule` modules to be able to do things like emit events, we need to expose the bridge instance.
To allow classes derived from `CxxModule` in other projects to include `<cxxreact/Instance.h> I also needed to convert all the header includes to non-relative ones.
Reviewed By: javache
Differential Revision: D4564145
fbshipit-source-id: a5bc28dd9b40e2b141af9e867105c56083fbdcdc
Pieter De Baets
Sean Kinsey
Chris Hopman