Fix iOS 17.1+ issues when using PanModal for view controller containers

[ppave]

Summary

Fix for iOS 17.1+ versions when using PanModal for view controller containers (UINavigationController, UIPageViewController, etc). In this case containerView inside PanModalPresentationController is nil and it breaks the logic, and as a result the bottom sheet is not displayed.

As we show bottom sheets, I think we always should have a presenting view controller. So the solution is to pass a source view controller in case of presenting view controller is not determined by OS.

Please note that there are cases when presenting view controller != source view controller, but I think for the case of this library it doesn't make much difference.

Tested on iPhone and iPad running on iOS 17.2.

Requirements (place an x in each [ ])

• [x] I've read and understood the Contributing Guidelines and have done my best effort to follow them.

• [x] I've read and agree to the Code of Conduct.

• [x] I've written tests to cover the new code and functionality included in this PR.

[salesforce-cla[bot]]

Thanks for the contribution! Before we can merge this, we need @ppave to sign the Salesforce Inc. Contributor License Agreement.

[salahelsayed99]

please could we merge this change or there is a problem ?