Refresh TCM settings when they change

Approach here is to register a content observer that invalidates the
TC settings whenever updates to the settings happen.

This CL also ensures that the TC is invalidated when a settings
update happens. This is because the settings may change what
TC the system returns.

TextView's SelectionActionModeHelper has been updated to not cache
the settings and get them directly from TCM (which caches the settings).

NOTE that we expect TC settings to rarely change.

Bug: 77539576
Test: bit FrameworksCoreTests:android.view.textclassifier.TextClassificationManagerTest
Test: bit CtsViewTestCases:android.view.textclassifier.cts.TextClassificationManagerTest
Test: bit CtsWidgetTestCases:android.widget.cts.TextViewTest
Test: bit FrameworksCoreTests:android.widget.TextViewActivityTest
Test: manual - Made changes to TC settings and observed logs / app behaviour

Change-Id: I88bbb6f951708b17323fac1a72385fe808d270a5