Convert ENR expansion NotificationEntry usages to EntryAdapter

And in doing so realized we don't actually need a getGroupRoot
method to get parent because the ENRs already have track who their
parent ENR is.

Test: GroupExpansionManagerTest
Test: GroupMembershipManagerTest
Test: StatusBarNotificationPresenterTest
Test: NotificationEntryTest
Test: BundleEntryTest
Test: HeadsUpManagerImplTest
Test: ExpandableNotificationRowTest
Bug: 395857098
Flag: com.android.systemui.notification_bundle_ui
Change-Id: I8d0dd0a37151d0bcc5533b2c2b8eedd790b310ee