Move ICU.getDisplay* API into external/icu

- The C-equivalent uloc_getDisplay* requires some explicit memory
management that has been handled by the C++ icu::Locale::getDisplay**
- This change abstract the C++ API into java for the callers in the java
world.

Bug: 138994281
Test: m droid
Change-Id: Ic5b40088f901b268b0d962435a48e55ba4650c47
5 files changed