Monkeypatch Win32::Registry methods delete_key, delete_value

[mcquin]

• Adds monkeypatches for Win32::Registry#delete_key and Win32::Registry#delete_value.
• Rewrites Chef::Win32::Registry#delete_key to use Win32::Registry#delete_key.

(Note: Once this is merged, I will move the Win32::Registry#write monkeypatch into lib/chef/monkey_patches/win32/registry.rb for consistency. Doing so here is outside the scope of this PR.)

[mcquin]

Most, if not all, of these spec failures are related to a bad chef-zero gem. I will rebase and re-run tests once the issue is resolved.

Please review @chef/client-windows

[chefsalim]

Should have file header

[chefsalim]

Looks good! 👍