Add SetRemoteVoicePosition support

[AnderSystems]

Hello! I was seeing that there is a great difficulty in implementing Spatial Audio, I don't understand much about the API, but I noticed that there is AgoraAudioEffects.SetRemoteVoicePosition(uid, pan, gain) in the documentation, however, it doesn't work in WebGL...
It would be great if this effect worked, as it seems to be simple to understand and implement in projects.

[icywind]

Unfortunately, that legacy code will never be supported in WebGL due to two main reasons:

1. The underlying Web SDK does not support panning on the audio stream.
2. The Spatial Audio extension is the way to do spatial audio in the long run.

So please spend some time to understand the examples and use the Spatial Audio APIs.