Make getLocalTextClassifier public

As suggested by security review, the javadoc should mention that
the requests will be sent to a textclassifier package if system
textclassifier is in use. Make getLocalTextClassifier public so that
developers can use it instead if they want to keep the data local.

BUG: 119631517
Test: atest TextClassificationManagerTest.java
Change-Id: I703c0a26c501c6eacf7c9efc7c21aca835e99fdb
2 files changed