(PUP-2544) Util::ADSI -> Util::Windows::ADSI
- Move Windows ADSI code out of puppet/util and into puppet/util/windows
- Update namespace from Puppet::Util::ADSI to Puppet::Util::Windows::ADSI
- Add module / class definitions for ADSI to util/windows.rb to prevent tests from blowing up on non-Windows
- Moving Puppet.features.microsoft_windows? checks to top of user and group provider tests for ADSI
- Update all dependent code, remove unnecessary references