[NNAPI] Use array instead of struct for serializing ints (#54696)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54696
This was originally developed for a Python version where array was not
available.
Test Plan: Unit test
Reviewed By: axitkhurana
Differential Revision: D27536792
Pulled By: dreiss
fbshipit-source-id: 39e5507e37d4f91871113439fe752a4d5373eaba
