[Feature Request] Change the default source used with the "@bot Play [song title]"

Nobody has claimed this yet.

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

Youtube playback being largely borked.

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

Enable users to choose a new default source for "@bot Play [song title]" from the supported options.

YouTube
SoundCloud
Bandcamp
Vimeo
Twitch streams
Local files
HTTP URLs

### How would this feature be used?

via the config.txt or with another bot command

### 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 reading config.txt handling and the command path for "@bot Play [song title]". Trace how the current default source is selected and how supported sources are represented. Done means users can choose the default from config.txt or another bot command, with YouTube, SoundCloud, Bandcamp, Vimeo, Twitch streams, local files, and HTTP URLs supported.

Written by the indexing model from the issue text.