Save original channel visibility on bundling notifications

If the original channel a notification is posted to is marked to never be shown on the lockscreen, we need to keep that information available after bundling even though the channel on the notification has changed (reset to the bundle channel).

Fixes: 410825977
Test: manual by posting notifications to secret channels & viewing the lockscreen; NotificationManagerServiceTest
Flag: android.app.notification_classification_ui
Change-Id: I01516507c03e3fcc1bde77a41687c5985d623d0d