Switch to use aicu/AIcu.h

Switch to using a dynamically-linked library function to initialize
ICU, not a statically-linked function. This means the knowledge of file
paths stays in the runtime module.

Bug: 120493361
Test: build/boot
Exempt-From-Owner-Approval: It's just a cherry-pick
Merged-In: Ibe1d5ffd50e5cce76b1b01788954dcfb4762b1c6
Change-Id: Ibe1d5ffd50e5cce76b1b01788954dcfb4762b1c6