Support SKOverlay in Original API

[OlenaPostindustria]

Objectives

We must provide a way to present and dismiss SKOverlay if the configuration is available in bid response.

1. Cache bid if skadn object is present.
2. Add new public API to InterstitialAdUnit and RewardedVideoAdUnit: activateSKOverlayIfAvailable and dismissSKOverlayIfAvailable.
3. When activateSKOverlayIfAvailable is called the SDK must start searching for the appearance of the GAM web view in the view hierarchy.
   • If web view is found, search for hb_local_cache_id in web view context and retrieve bid.
   • Present SKOverlay with a given configuration.
4. When dismissSKOverlayIfAvailable is called - stop any view hierarchy traversing and dismiss SKOverlay if presented.

Related issues: #997, #853

[OlenaPostindustria]

Implementation Issues

During the implementation process, we faced a challenge in accurately determining whether a video ad contains an end card and when it is presented. This complicates the process of defining the appropriate delay for presenting the SKOverlay.

[OlenaPostindustria]

It was decided to not support endcarddelay in the Original API. If delay is present, the SDK will use it, otherwise SKOverlay will be displayed immediately.