Roboletric apparently does not support Os.symlink, and some devices might
have wonky implementations. Copying is slower and takes more disk space,
but is much more reliable. So it is a workable fallback.
This affects anti-features and categories. Reflection diffing has been made more robust in the process with the earlier FileV2 hack removed and better error messages.
and remove sharedTest symlink hack. The shared tests are now a proper gradle module to avoid issues with using the same source files in different modules.
