fix(core): swipe to go back gesture has priority over other horizontal swipe gestures (#28304)

Issue number: resolves #28303

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## What is the current behavior?

- Swipe back gesture is inconsistently clobbered by ion-item-sliding's
gesture.

## What is the new behavior?

- Swipe back gesture now has a higher priority than ion-item-sliding
-
-

## Does this introduce a breaking change?

- [ ] Yes
- [X] No

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and migration path for existing applications below. -->


## Other information

This patch has been in use in
[Voyager](https://github.com/aeharding/voyager) for the past couple
months to great success!

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Co-authored-by: Liam DeBeasi <liamdebeasi@users.noreply.github.com>