Fix for https://github.com/duckduckgo/zeroclickinfo-goodies/issues/772.

The fix consists of new class DDG::CountryCodes and basic unit tests.

This class factors out some spice and goodie usages of Locale::Country
where there was some organic copying. DDG-local aliases and renames
are centralized here.

Locale::Country is presented as a functional style library, but some of its
calls modify its state, so it's probably cleaner to use it wrapped as an
object for encapsulation.

*** NOTE *** - There are also followup PRs in spice and goodie which
    will depend on this patch.  Merge this one first please.
Please add this, and any other new deps to the dist.ini