Support Opus FEC and PLC

### Feature

The Opus library supports forward-error correction (FEC) and packet loss concealment (PLC).

This is useful if the audio being decoded was sent at some point over an unreliable channel, e.g. WebRTC. These functions allow the missing audio to be interpolated, creating a better experience for the listener.

I have written a PR to add these functions (https://github.com/discordjs/opus/pull/195) but I saw that issues are usually wanted before PRs, so I filed this as well -- sorry for doing things out of order!

### Ideal solution or implementation

API enhancements to add these features -- see my PR for my suggested API, though I'm open to alternatives.

### Alternative solutions or implementations

_No response_

### Other context

_No response_