Cached static Objective-C xcframeworks build correctly (ARCore)

Google ARCore (and similar Google SDK xcframeworks) can now be cached and consumed through the binary cache. Static Objective-C xcframeworks whose headers live in Headers/<Module>/ subdirectories and re-import siblings with the <Module/...> prefix are now consumed through their own module map with the xcframework’s Headers root on the header search path. Earlier RCs failed with 'ARCoreGARSession/GARTrackingState.h' file not found or import of shadowed module 'GARAnchor'.