Remove dependency of bundled program from testing:tensors_are_close (#165)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/165

Bundled program was using tensors_are_close from the testing utils folder which depends on gmock which isn't supported in OSS. Copying over that implementation into a private copy in `bundled_program_verification.cpp`

Reviewed By: Gasoonjia, cccclai

Differential Revision: D48768256

fbshipit-source-id: bd43d5d91963eebc15ec5c2156e3e53876bfc173