fix(react, vue): inline modals apply ion-page class (#27481)

Issue number: resolves #27470

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## What is the current behavior?
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Passing multiple elements in to an inline modal causes `.ion-page` to
not get set. This causes content to get pushed off the bottom of the
modal equal to the height of the header. React has some special CSS that
prevents this:
eb2772c0ce/packages/react/src/components/createInlineOverlayComponent.tsx (L137-L140)

However, I think this should be delegated to `.ion-page` instead so the
behavior is consistent across frameworks. For example, Angular uses
`.ion-page`:
eb2772c0ce/angular/src/directives/overlays/modal.ts (L82)

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

- Inline overlays in Ionic React and Ionic Vue wrap child content in
`.ion-delegate-host.ion-page`.
- Removed the custom flex styles from Ionic React as `.ion-page` has its
own styles.

## 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. -->

Revised Design Doc:
https://github.com/ionic-team/ionic-framework-design-documents/pull/84

packages/vue/src/components/Overlays.ts

@@ -27,7 +27,7 @@ export const IonPicker = /*@__PURE__*/ defineOverlayContainer<JSX.IonPicker>('io
     
 export const IonToast = /*@__PURE__*/ defineOverlayContainer<JSX.IonToast>('ion-toast', defineIonToastCustomElement, ['animated', 'buttons', 'color', 'cssClass', 'duration', 'enterAnimation', 'header', 'htmlAttributes', 'icon', 'isOpen', 'keyboardClose', 'layout', 'leaveAnimation', 'message', 'mode', 'position', 'translucent', 'trigger']);
     
-export const IonModal = /*@__PURE__*/ defineOverlayContainer<JSX.IonModal>('ion-modal', defineIonModalCustomElement, ['animated', 'backdropBreakpoint', 'backdropDismiss', 'breakpoints', 'canDismiss', 'enterAnimation', 'handle', 'handleBehavior', 'htmlAttributes', 'initialBreakpoint', 'isOpen', 'keepContentsMounted', 'keyboardClose', 'leaveAnimation', 'mode', 'presentingElement', 'showBackdrop', 'trigger']);
+export const IonModal = /*@__PURE__*/ defineOverlayContainer<JSX.IonModal>('ion-modal', defineIonModalCustomElement, ['animated', 'backdropBreakpoint', 'backdropDismiss', 'breakpoints', 'canDismiss', 'enterAnimation', 'handle', 'handleBehavior', 'htmlAttributes', 'initialBreakpoint', 'isOpen', 'keepContentsMounted', 'keyboardClose', 'leaveAnimation', 'mode', 'presentingElement', 'showBackdrop', 'trigger'], true);
     
 export const IonPopover = /*@__PURE__*/ defineOverlayContainer<JSX.IonPopover>('ion-popover', defineIonPopoverCustomElement, ['alignment', 'animated', 'arrow', 'backdropDismiss', 'component', 'componentProps', 'dismissOnSelect', 'enterAnimation', 'event', 'htmlAttributes', 'isOpen', 'keepContentsMounted', 'keyboardClose', 'leaveAnimation', 'mode', 'reference', 'showBackdrop', 'side', 'size', 'translucent', 'trigger', 'triggerAction']);