Move long-click handling to BundleHeader

This allows talkback/accessibility focus to know that the row is long-clickable in addition to clickable. It calls through to the same existing long-click handler on ExpandableNotificationRow that was handling the functionality before.

Fixes: 424352595
Test: manual, confirmed talkback on header says "double-tap to activate. double-tap and hold to long press", and also that guts opens as expected and behaves normally
Flag: com.android.systemui.notification_bundle_ui
Change-Id: I3b51d240dd0ea7772274d3e78cff604d78e77e13