dirsync-ify folly/result

Summary:
Converting 16 targets from dual fbcode_target/non_fbcode_target definitions to
unified fb_dirsync_cpp_library.

Reviewed By: snarkmaster

Differential Revision: D91920335

fbshipit-source-id: c6e6cd7bb9ce874967696b92ecac5a54485955ea

Author: mzlee