Export libtextclassifier

Export libtextclassifier without the model downloader code to
mainline-prod for a few changes we want for the upcoming mainline
release.

Test: atest -p external/libtextclassifier
Test: Smart selection + smart reply on a R device

Fixes: 179890518

Change-Id: I0da4487432920e3f95cb00d4f44c8ec257f4b81b
53 files changed