Add ClientGetReadReactor.cpp to project.pbxproj again

Summary: When rebasing expo migration code to master I mistakenly deleted ClientGetReadReactor.cpp from project.pbxproj file when resolving confilcts. This urgent diff bring it back and solves iOS build failure on CI"

Test Plan: Sucessfully build app

Reviewers: palys-swm, atul, ashoat

Reviewed By: palys-swm, ashoat

Subscribers: benschac, ashoat, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3286