[Bug] Cannot change shadow appearance on Frame from version 4.5.x

[badstorm]

Description

In my custom render I have this settings for change the appearance of the shadow in iOS

protected override void OnElementChanged(ElementChangedEventArgs<Frame> e)
{
    base.OnElementChanged(e);
    Layer.ShadowRadius = 10f;
    Layer.ShadowColor = UIColor.Black.CGColor;
    Layer.ShadowOffset = new CGSize(0,10);
    Layer.ShadowOpacity = 0.16f;
}

but from Xamarin Forms 4.5.x not works anymore.

What I see is that in the FrameRenderer was added a new ShadowView that in not accessible from the custom renderer.

Workaround

In The FrameRender add a public function like this for access the ShadowView::

public ShadowView InnerShadowView
{
   get => _shadowView;
}

So in the custom renderer I can do:

protected override void OnElementChanged(ElementChangedEventArgs<Frame> e)
{
    base.OnElementChanged(e);
    InnerShadowView.Layer.ShadowRadius = 10f;
    InnerShadowView.Layer.ShadowColor = UIColor.Black.CGColor;
    InnerShadowView.Layer.ShadowOffset = new CGSize(0,10);
    InnerShadowView.Layer.ShadowOpacity = 0.16f;
}

[samhouts]

related to #7518

[jfversluis]

Added reproduction here (note; uses a local nupkg file so will probably fail to restore that) and tried with the NuGet resulting from #10469. Works as expected.

With the fix from the afore mentioned PR it is likely that all renderers should work as before.

Repro10348.zip