[Feature Request] Whitelist/filter for music source domains

**Is your feature request related to a problem? Please describe.**
Currently I have the perms for the channel set to disallow people from uploading files but that then blocks them from sharing pictures so it isn't the best solution

**Describe the solution you'd like**
It would be nice to have a config option to be able to block playing of local files. I run a fairly large server and don't really want people to be able to upload songs and play them. I don't want copyright issues to come up.

**Describe the basic flow/steps of using this feature**
How this feature would be used:
set the option in config so it wont load a local file if someone uploads it

**Additional context**
with it being a feature that it can do and people can see that the bot supports it, they'll try to do it.

**Have you confirmed that this idea is not already described here?**
yes

Start by locating the configuration handling and the code that loads music sources, then trace how uploaded local files are accepted for playback. The feature is done when a configuration option prevents local-file playback while still allowing image uploads in the channel.

Written by the indexing model from the issue text.