(PUP-839) Remove SID mixin from Security

 - SID methods can really standalone on their own, and
   should for the sake of sanity / code maintenance.  Adjust all
   callsites (including specs) accordingly.
 - Make SID methods into static module_functions since they're
   already stateless
(PUP-839) Deprecations for Security SID methods

 - Make sure any consumers relying on these methods have warnings,
   so that we can rip these out in Puppet 4
(PUP-2387) Windows::File use FFI::Pointer helper

 - Remove custom packing of array bytes and replace with use of
   read_wide_string from FFI::Pointer