[android][fbjni] Test_app and Readme update with the recent fbjni dep state (#40058)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/40058
Test Plan: Imported from OSS
Differential Revision: D22054574
Pulled By: IvanKobzarev
fbshipit-source-id: 751e5bd5103aa869702356fc181f458fe4fcfc83
