Make ZoneInfoData immutable

With this change:
- mRawOffset becomes final

Also,
- Remove unused @IntraCoreApi from ZoneInfoData
- The APIs are now replaced by other APIs.

Bug: 139480281
Test: atest CtsLibcoreTestCases CtsIcuTestCases
Change-Id: Ibc7e945edad192012e2192b4c117d62d27e60124
4 files changed