(Work in Progress) (FACT 614) Add structured operatingsystem fact

The first of these commits adds the 'os' structured fact, which incorporates all operatingsystem-related facts into a nested hash. Includes keys for the equivalents of operatingsystem, osfamily, operatingsystemrelease, operatingsystemmajrelease, and the six lsb facts for Linux systems.

The second commit refactors the previously mentioned existing flat facts to resolve by using values from the new 'os' structured fact. This ensures that these facts will stay in sync with the new fact, while also maintaining backwards compatibility.
Can this use a memoized method like https://github.com/puppetlabs/facter/commit/d3f534eb74d0de5de3128fa941ae708840e02031 uses?