Metadata UWP audio not showing

## 🐛 Bug Report

The method **_CreateMediaItem_** by adding the url path is working only when the audio file doesn't have a thumbnail or album pic, otherwise it tries to get the rest of the metadata and then crashes.

(Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))
at Windows.UI.Xaml.Media.Imaging.BitmapImage..ctor()
at MediaManager.Platforms.Uap.Media.StorageFileProvider.ProvideImage(IMediaItem mediaItem)
at MediaManager.Media.MediaExtractorBase.GetMediaImage(IMediaItem mediaItem)
at MediaManager.Media.MediaExtractorBase.UpdateMediaItem(IMediaItem mediaItem)
at MediaManager.Media.MediaExtractorBase.CreateMediaItem(String url)

### Configuration
Xamarin Forms 4.8.0.1269

**Version:** 0.9.6

**Platform:**
- [x] :earth_americas: UWP
- [x] :monkey: Xamarin.Forms

Reproduce the UWP audio case with a thumbnail or album image, then inspect MediaManager.Platforms.Uap.Media.StorageFileProvider.ProvideImage and the MediaExtractorBase.CreateMediaItem/UpdateMediaItem path shown in the stack trace. Done means metadata extraction no longer raises RPC_E_WRONG_THREAD while processing the image.

Written by the indexing model from the issue text.