Implements TextClassifierImpl.suggestConversationActions

TODO: Construct RemoteAction for contextual actions.
TODO: Map Person object to user id.
TODO: Consider to use LangID to infer the locale. And get a new model when locale is changed.

BUG: 111437455
BUG: 111406942

Test: atest ./core/tests/coretests/src/android/view/textclassifier/TextClassificationManagerTest.java

Change-Id: Id35066455918b3321fcd30df0ff215e30586a4b3