[V6][iOS] modalPresentationStyle popover results in app crash - UIPopoverPresentationController should have a non-nil sourceView

Issue Description

When setting modalPresentationStyle to popover the application crashes when opening a modal.

xCode reports following:
*** Terminating app due to uncaught exception 'NSGenericException', reason: 'UIPopoverPresentationController (<UIPopoverPresentationController: 0x7f9dfa32d200>) should have a non-nil sourceView or barButtonItem set before the presentation occurs.'

Steps to Reproduce / Code Snippets / Screenshots

Following is directly from playground ModalScreen.js with the options modalPresentationStyle set to popover

  showModal = () => {
    Navigation.showModal({
      component: {
        name: Screens.Modal,
        passProps: {
          modalPosition: this.getModalPosition() + 1,
          previousModalIds: concat([], this.props.previousModalIds || [], this.props.componentId)
        },
        options: {
          modalPresentationStyle: 'popover'
        }
      }
    });
  }

Environment

• React Native Navigation version: 6.7.5 & 6.8.0
• React Native version: 0.62.2
• Platform(s) (iOS, Android, or both?): iOS
• Device info (Simulator/Device? OS version? Debug/Release?): Simulator 13.3 / Device 13.3

Start with the modal presentation path exercised by playground ModalScreen.js and the modalPresentationStyle: 'popover' option. Reproduce the crash on iOS using the supplied example, then trace how the popover presentation is configured. Done means opening this modal no longer raises the UIPopoverPresentationController exception.