[Pluggable Device] Add DEFAULT_DEVICE registrations for some ops.
> Ask discussed offline, all registrations in this PR had caused internal test failures and were reverted before, and the issues haven't been fixed yet. Please guard all device default registrations in this PR with macos ifdefs for now.

Thanks @penpornk , added them to be specific to macos. For the record: I had made the requested changes internally before merging the PR. > For the record: I had made the requested changes internally before merging the PR.

Thanks Penporn. Much appreciated.
Adding some more registrations for commonly used ops to DEFAULT_DEVICE using CPU implementation.  
cc @penpornk 