Export libtextclassifier and make some native tests working again

The export script is updated, so that

1. "android-ready" native tests are now exported to Android.
2. Some dead code are removed
3. test_data is removed for now. Our tests that load a test file
   in runtime have never worked on Android. Will bring them back
   once I get them working.

Test: atest TextClassifierService
Test: atest libtextclassifier_tests

BUG: 157134682

Merged-In: I98b25793e9644bee43f416255911d969b31d91b7

Change-Id: I98b25793e9644bee43f416255911d969b31d91b7
77 files changed