Use ICU in libandroidicu

libicuuc and libicui18n are moved into APEX, but
they have no stable ABI due to the version suffix.

Use libandroidicu which provides stable symbol.
See http://go/apex-stable-icu4c-interface for the design.
See http://aosp/801855 for libandroidicu implementation.

Bug: 117094880
Test: m checkbuild
Merged-In: I2f02cfcbb736df8a1bc9404afb6d2d0f46a3443b
Change-Id: I2f02cfcbb736df8a1bc9404afb6d2d0f46a3443b
(cherry picked from commit c792c5ca)