[Feature request]: Support yt-dlp custom instances

### What do you need?

[Users have the ability to use `yt-dlp` with Invidious instances through plugins](https://github.com/yt-dlp/yt-dlp/issues/7403#issuecomment-1751822358) and works fine

But when I provide it to Fabric, it intercepts it with a failure message:

```
invalid YouTube URL, can't get video or playlist ID
```

Makes sense that [this is done](https://github.com/danielmiessler/Fabric/blob/main/internal/tools/youtube/youtube.go#L53) but it would also be nice to skip altogether this validation and let the user break it through environment variables

This is a niche request, but maybe someone else finds it useful 🤷
Thank you for the hard work and this great tool!