[Feature Request] Shuffle Local Files With Linked Playlist

### Is your feature request related to a problem? Please describe.

For people that have one or two local songs in a txt playlist mixed into a YouTube or SoundCloud playlist and try to shuffle the combined playlist, it will only shuffle the linked playlist and then add the local file either at the start or end of the queue depending on where in the txt it is called in to play.

### What is your ideal solution to the problem?

It should instead shuffle the entire playlist instead of only shuffling the linked playlist. It would be more ideal than having to run the shuffle command manually to then shuffle the entire thing once more to have the local file in a more random position.

### How would this feature be used?

It would be setup and used as previously, with the only change being that local files are shuffled in with the linked playlist.

### Additional Info

_No response_

### Checklist

- [X] I have checked [the documentation](https://jmusicbot.com/) to make sure this feature doesn't already exist
- [X] I have searched for [similar feature requests](https://github.com/jagrosh/MusicBot/labels/enhancement)
- [X] I have confirmed that my requests is **not** on the [list of things that will not be added](https://jmusicbot.com/things-that-wont-be-added)
- [X] I am running the latest version of the bot: 

Start by tracing how txt playlists are loaded and how the shuffle command handles linked YouTube or SoundCloud entries. Compare the queue behavior for local files and linked tracks; done means one shuffle randomizes the complete combined playlist, including local files, without requiring a second manual shuffle.

Written by the indexing model from the issue text.