Add @IntraCoreApi createInstance() to avoid binary input

It avoids dependency on unstable tzdata-testing library
from the CtsLibcoreTestCases.

Bug: 177220561
Test: atest CtsLibcoreTestCases:libcore.libcore.util.ZoneInfoTest
Change-Id: Ieb72e28e06a5c28f9e9ccc287654bb4e69b42aa7
2 files changed