fix(picker-column): fallback to elementFromPoint for iOS 16 Shadow DOM bug (#30479)

Issue number: resolves #29672

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## What is the current behavior?
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The issue on iOS 16 with `elementsFromPoint` is related to how it
handles Shadow DOM retargeting when called from the document (global)
context.

It leads to an `undefined` element that is required to trigger
`ionChange`.

## What is the new behavior?
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this PR. -->

- Returns the top most element as a fallback only if the element has a
tag of `'ion-picker-column-option'`.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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

Dev build: `8.6.2-dev.11749761258.1b46b6a9`

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Co-authored-by: Vilhelm Josander <5067135+vilhelmjosander@users.noreply.github.com>

core/src/components/picker-column/picker-column.tsx

@@ -376,7 +376,27 @@ export class PickerColumn implements ComponentInterface {
          * elementsFromPoint can returns multiple elements
          * so find the relevant picker column option if one exists.
          */
-        const newActiveElement = elementsAtPoint.find((el) => el.tagName === 'ION-PICKER-COLUMN-OPTION');
+        let newActiveElement = elementsAtPoint.find((el) => el.tagName === 'ION-PICKER-COLUMN-OPTION');
+
+        /**
+         * TODO(FW-6594): Remove this workaround when iOS 16 is no longer
+         * supported.
+         *
+         * If `elementsFromPoint` failed to find the active element (a known
+         * issue on iOS 16 when elements are in a Shadow DOM and the
+         * referenceNode is the document), a fallback to `elementFromPoint`
+         * is used. While `elementsFromPoint` returns all elements,
+         * `elementFromPoint` returns only the top-most, which is sufficient
+         * for this use case and appears to handle Shadow DOM retargeting
+         * more reliably in this specific iOS bug.
+         */
+        if (newActiveElement === undefined) {
+          const fallbackActiveElement = referenceNode.elementFromPoint(centerX, centerY);
+
+          if (fallbackActiveElement?.tagName === 'ION-PICKER-COLUMN-OPTION') {
+            newActiveElement = fallbackActiveElement as HTMLIonPickerColumnOptionElement;
+          }
+        }
 
         if (activeEl !== undefined) {
           this.setPickerItemActiveState(activeEl, false);