Request Sample: Video Call

> Please provide us with the following information:
Request Sample: Video Call
> ---------------------------------------------------------------

### This issue is for a: (mark with an `x`)
```
- [ ] bug report -> please search issues before submitting
- [x ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
> Na

### Any log messages given by the failure
>Na

### Expected/desired behavior
> C# SDK Video Call Sample

### OS and Version?

> Windows 10
### Versions
> 1903 +

### Mention any other details that might be useful
Can we have a video call Sample? It's better to support WPF
I'm making a demo based on azure communication service for multi user video call scenario
> ---------------------------------------------------------------
> Thanks! We'll be in touch soon.

No file, test, or entry point is named. Start by reviewing the repository's existing .NET quickstarts and the Azure Communication Services video-call requirements, then define the WPF multi-user sample scope and validate that the completed sample supports the requested Windows 10 scenario.

Written by the indexing model from the issue text.