Apple changed the name of their operating system from OS X to macOS a number of years ago. This was overdue!

As per issue  #10311

* refactor(osx): rename `osx` plugin to `macos`
* refactor(macos): Add symbolic link from old `osx` plugin name.

Co-authored-by: Capybara <git.capybara@gmail.com>
Co-authored-by: drootang <drootang@users.noreply.github.com>
Co-authored-by: Augusto Souza <augustorsouza@gmail.com>
Co-authored-by: PatrBal <44707588+PatrBal@users.noreply.github.com>