WIP: fixup with other Wind code - fix for Windows FNF on get_file_attributes for symlinks
(#19447) Puppet::FileSystem::File.exists?

 - All calls to exists? go through the new
   FileSystem::File abstraction so that the implementation can later
   be swapped for a Windows specific one to support symlinks
WIP: more work around File.exists
WIP: fixup with exist? code