Redirect /world to /government/world
Redirect /world to /government/world

This commit adds a redirect from `/world` to `/government/world`. This is in preparation for the migration of all content from `/government/world` to `/world`. Before this migration, the existing router prefix redirect will be removed, therefore whitehall will handle redirecting from one prefix to the other.

alphagov/whitehall,alphagov/whitehall,alphagov/whitehall,alphagov/whitehall