feat(angular, react, vue, core): export openURL utility (#28295)

Issue number: resolves #27911 

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## What is the current behavior?
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The `openURL` utility is not available to developers. 

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

- Export `openURL` utilities from `@ionic/core`, `@ionic/angular`,
`@ionic/react` and `@ionic/vue`.

## 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. -->

core/src/index.ts

@@ -11,6 +11,7 @@ export { componentOnReady } from './utils/helpers';
 export { isPlatform, Platforms, PlatformConfig, getPlatforms } from './utils/platform';
 export { IonicSafeString } from './utils/sanitization';
 export { IonicConfig, getMode, setupConfig } from './utils/config';
+export { openURL } from './utils/theme';
 export {
   LIFECYCLE_WILL_ENTER,
   LIFECYCLE_DID_ENTER,

packages/angular/src/index.ts

@@ -131,4 +131,5 @@ export {
   ToggleChangeEventDetail,
   ToggleCustomEvent,
   TransitionOptions,
+  openURL,
 } from '@ionic/core';

packages/react/src/components/index.ts

@@ -10,6 +10,7 @@ export {
   IonicSlides,
   getTimeGivenProgression,
   getIonPageElement,
+  openURL,
 
   // TYPES
   Animation,

packages/vue/src/index.ts

@@ -48,6 +48,7 @@ export {
   menuController,
   getTimeGivenProgression,
   getIonPageElement,
+  openURL,
 
   // TYPES
   Animation,