[SB][Notif] Stable-sort notif chips by first appearance time.

Bug: 364653005
Bug: 385724468
Flag: com.android.systemui.status_bar_notification_chips

Test: Trigger 2 notif chips, then tap each one in turn -> verify chip
order never changes
Test: Trigger 2 notif chips, and send updates for the one that was
originally posted earlier -> verify earlier-posted notif chip always
stays second
Test: atest StatusBarNotificationChipsInteractorTest

Change-Id: I45a7244531904a9e042f50205666169f0c8262e2