fix: server actions blocking navigation events (#54307)
A long-running server action shouldn't block page navigation. This makes use of a global mutable to detect when a navigation event occurs -- this change will unblock other reducers (such as navigation).
If we bailed on the action, we trigger a `router.refresh()` to ensure any side effects from the action are refetched.
Closes NEXT-1131
Fixes #49425
