TextClassifier updates

- Increase the size of the text sent as context to the classifier
- Pass regex match hints to the classifer

Test: Build still works. Regex hints logged correctly. The hints won't
matter until we've actually passed in this values to native code. Native
library test will be written and I've got a tracker bug to write more robust Java tests.

Bug: 35416389
Bug: 36584397

Change-Id: I29e56189b388b36dc0cc7a8bb13ef237ff55be7b