Proposal to add `shrinkWrap` property for platform views

[bdlukaa]

Use case

Currently, when using a platform view, it's necessary to give it a size using a SizedBox or a Container. It'd be great if we could introduce it to the tree without needing to give it a size. For example, using the plugin native_admob_flutter, it's necessary to give the ad a size. The same with google_mobile_ads with Native Ads

Proposal

I'd like to be able to just set shrinkWrap to true in a PlatformView and insert it in the Widget tree without problems:

// For android:
AndroidView(
   shrinkWrap: true,
   viewType: widget.viewType,
   creationParamsCodec: StandardMessageCodec(),
   creationParams: widget.params,
);

// For iOS:
UiKitView(
  shrinkWrap: true,
  viewType: _viewType,
  creationParamsCodec: StandardMessageCodec(),
  creationParams: params,
)