Support all RTL scripts in getLayoutDirectionFromLocale().

Previously, only the languages written in Arabic and Hebrew were
considered right-to-left. Now, ICU is used to return the direction
of the language, which not only support other right-to-left scripts
(such as Thaana), but also has better logic to determine the
direction of the locale and uses caching to improve the speed.

Bug: 22559274
Change-Id: I760be7984a9b35ea77d59ca84a220798e205af36