(FACT-699) Add `rubyplatform` and `system32` facts

Adds `system32` fact on Windows to report on the *native* system32 directory across 32/64 bit versions of ruby and windows.

Adds a `rubyplatform` fact for all platforms so that manifests can create conditions based on 32 vs 64-bit ruby.
I was following `rubyversion` as an example https://github.com/puppetlabs/facter/blob/master/lib/facter/rubyversion.rb#L11, and didn't want to reinvent the x86 vs x64 semantics for the `architecture` fact