Start migrating tests from helpers to kosmos

So that we're no longer getting NotificationEntries from
rows and no longer need to pass a context around.

Test: NotificationGroupingUtilTest
Test: ExpandHelperTest
Test: AboveShelfObserverTest
Test: ExpandableNotificationRowDragControllerTest
Test: ExpandableNotificationRowTest
Bug: 395857098
Flag: com.android.systemui.notification_bundle_ui

Change-Id: Ib4531e758beb6d799615330733137c54e966453d