Fix suggestions in the language selector

The current implementation makes the decision based on the
list of locales translated in frameworks/base

It will break if we remove country from the resource locale IDs
(e.g. fr-FR => fr)
It also offers no flexibility in case we want to suggest a country
based on other criteria.

Bug: 27378061
Change-Id: I3d8514e8abff83a4c98c5658533738611cf12576