Add World.prepend_mod to allow JH override

Changelog: other
EE: true

ee/lib/world.rb

@@ -31,3 +31,5 @@ module World
     ISO3166::Country[alpha2]&.alpha3
   end
 end
+
+World.prepend_mod

ee/spec/controllers/countries_controller_spec.rb

@@ -19,8 +19,8 @@ RSpec.describe CountriesController do
       # response is returned as [["Afghanistan", "AF"], ["Albania", "AL"], ..]
       resultant_countries = json_response.map {|row| row[0]}
 
-      expect(resultant_countries).not_to include(World::DENYLIST)
-      expect(resultant_countries).not_to include(World::JH_MARKET)
+      expect(resultant_countries).not_to include(*World::DENYLIST)
+      expect(resultant_countries).not_to include(*World::JH_MARKET)
     end
   end
 end