iOS Broadcast Upload Extension is not working / no project template

### Steps to Reproduce

1. Try to create Broadcast Upload Extension for xamarin or maui
2. It’s not working for xamarin or maui
3. Try this example https://github.com/DreamTeamMobile/Xamarin.Agora.Samples/tree/master/ScreenSharing

### Expected Behavior
It would be nice if it worked

### Actual Behavior
we needed an iOS extension for screen sharing and a binding for video streaming native sdk, and it didn't work on maui at all.

The video worked in xamarin, but the iOS extensions still didn't work.

For maui there is no project for extrnstions,
Thanks Valdyslav for creating it.
https://github.com/dotnet/maui/discussions/3289

It turns out that in some way native iOS extensions are broken or have never worked.

### Environment
vs for mac
.net 6
.net 7