Restore notifications when disabling a bundle from guts

Rather than dismissing them entirely, notifications that were previously bundled should be returned to their regular positions in the shade.

This change adds EntryAdapter.onBundleDisabled, which triggers onImportanceChanged for all the children in the bundle and any nested children in groups inside the bundle.

Bug: 417715201
Test: manual by disabling a bundle from guts and observing notifications
Flag: com.android.systemui.notification_bundle_ui
Change-Id: Ic0c4f11b2d23883b45a8c882eed99ed1265160fa