fix(item-sliding): account for options added before watcher (#27915)

Issue number: resolves #27910

---------

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

There is an edge case in our `ion-item-sliding` code where options can
be added after the `querySelectorAll` has been run in `updateOptions`
but before `watchForOptions` has been called which causes us to miss the
newly created options. These options can never be shown as a result.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- `watchForOptions` is called before the initial `updateOptions` call so
that we can re-run `updateOptions` in the event that options are added
while that first call is running.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

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screenshots of how the component looks before and after the change. -->

Dev build: `7.2.2-dev.11690983626.19a2a8cb`

core/src/components/item-sliding/item-sliding.tsx

@@ -76,12 +76,19 @@ export class ItemSliding implements ComponentInterface {
     this.item = el.querySelector('ion-item');
     this.contentEl = findClosestIonContent(el);
 
-    await this.updateOptions();
-
+    /**
+     * The MutationObserver needs to be added before we
+     * call updateOptions below otherwise we may miss
+     * ion-item-option elements that are added to the DOM
+     * while updateOptions is running and before the MutationObserver
+     * has been initialized.
+     */
     this.mutationObserver = watchForOptions<HTMLIonItemOptionElement>(el, 'ion-item-option', async () => {
       await this.updateOptions();
     });
 
+    await this.updateOptions();
+
     this.gesture = (await import('../../utils/gesture')).createGesture({
       el,
       gestureName: 'item-swipe',