Improve the cache and memory management for Native Ads

[YuriyVelichkoPI]

Objectives

Deprecate Method:

public boolean registerView(View view, final PrebidNativeAdEventListener listener)

Update rename method

public boolean registerViewList(View container, List<View> viewList, final PrebidNativeAdEventListener listener)

to:

public boolean registerView(View view, List<View> clickableViews, final PrebidNativeAdEventListener listener)

view - the native ad container used to track impression
clickableViews - list of views that should handle click

• Don't catch the registered view registeredView by the strong reference in the PrebidNativeAd.
• Don't catch the registered view view by the strong reference in VisibilityDetector.
• Don't catch the registered views in the clickableViews by the strong references.
• Ensure that destroying the PrebidNativeAd all listeners and registered views are destroyed as well. No memory leaks should be here.
• Ensure that the CacheManager signal the respective PrebidNativeAd objects on the expiration event.
• Update tests

[ValentinPostindustria]

When a user uses registerView() with an anonymous listener parameter in Activity or Fragment, he can create a memory leak that we can't control. To prevent it a user should use a class that extends PrebidNativeAdEventListener.

class NativeListener : PrebidNativeAdEventListener {

        override fun onAdClicked() {}

        override fun onAdImpression() {}

        override fun onAdExpired() {}

}

And then use:

nativeAd.registerView(
            binding.adContainer,
            listOf(
                binding.tvNativeTitle,
                binding.ivNativeMain,
                binding.ivNativeIcon
            ),
            NativeListener() // ***
)