TextClassifier: Multiple entities & confidence scores.

 - Updates JNI layer to support multiple entities & confidence scores
 - Updates code to include multiple entities & confidence scores
 - Fixes EntityConfidence sorting to be descending order

Test: cts-tradefed run cts-dev -m CtsViewTestCases -t
android.view.textclassifier.cts.TextClassificationManagerTest
Bug: 35153211

Change-Id: I4878fe7573f5cb7f3eafb1b50c7baf331a336cb1