Add app level settings for classification and summarization

Test: AdjustmentKeyPreferenceControllerTest
Flag: android.app.nm_summarization
Flag: android.app.notification_classification_ui
Flag: android.app.nm_summarization_ui
Bug: 377697346
Bug: 390412878
Change-Id: I85b67b5c0376ee4cd962e26bf178aae6fa712212