router restore should take priority over pending actions (#64449)
Since the router processes events sequentially, we special case
`ACTION_NAVIGATE` events to "discard" a pending server action so that it
can process the navigation with higher priority. We should apply this
same logic to `ACTION_RESTORE` events (e.g. `router.back()`) for the
same reason.
Fixes #64432
Closes NEXT-3098