feat(checkbox): add required prop (#30157)

Issue number: resolves internal

---------

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## What is the current behavior?
- Currently, the screen reader do not announce the component as required
when `required={true}`.

## What is the new behavior?
- Added a new `required` prop to be used for accessibility purposes that
adds the `required` attribute to checkbox's inner native input.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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packages/angular/src/directives/proxies.ts

@@ -507,14 +507,14 @@ export declare interface IonCardTitle extends Components.IonCardTitle {}
 
 
 @ProxyCmp({
-  inputs: ['alignment', 'checked', 'color', 'disabled', 'indeterminate', 'justify', 'labelPlacement', 'mode', 'name', 'value']
+  inputs: ['alignment', 'checked', 'color', 'disabled', 'indeterminate', 'justify', 'labelPlacement', 'mode', 'name', 'required', 'value']
 })
 @Component({
   selector: 'ion-checkbox',
   changeDetection: ChangeDetectionStrategy.OnPush,
   template: '<ng-content></ng-content>',
   // eslint-disable-next-line @angular-eslint/no-inputs-metadata-property
-  inputs: ['alignment', 'checked', 'color', 'disabled', 'indeterminate', 'justify', 'labelPlacement', 'mode', 'name', 'value'],
+  inputs: ['alignment', 'checked', 'color', 'disabled', 'indeterminate', 'justify', 'labelPlacement', 'mode', 'name', 'required', 'value'],
 })
 export class IonCheckbox {
   protected el: HTMLIonCheckboxElement;