[iOS] Set _LIBCPP_ENABLE_CXX17_REMOVED_UNARY_BINARY_FUNCTION flag to unblock iOS build

Summary:
Linear: https://linear.app/comm/issue/ENG-4984/xcode-version-15-update
GitHub: https://github.com/facebook/react-native/issues/37748

Depends on D9227

Test Plan: iOS builds succeeds after yarn cleaninstall without issue.

Reviewers: ashoat, ginsu, tomek, bartek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D9228