[Feature Request] -clean command to clean up channel

Whenever I use this bot, I end up having a whole channel spammed with `-play` requests, to clean up I have to go and manually delete each message.

Adding a `-clean` command to clean up the channel, similar to [Rhythm Bot !clean command](https://rythmbot.co/features). This command would delete all messages related to the bot including `-play`, the "Now playing" and any other commands.

How this feature would be used:
1. Someone requests a song via `-play `
2. Someone runs the `-clean` command to delete all the messages made

Start by locating the command handling for `-play` and the messages that produce the "Now playing" output. Review the linked Rhythm Bot `!clean` behavior for comparison, then determine how the bot can identify and delete its related messages. Done means `-clean` removes the listed bot messages from the channel without requiring manual deletion.

Written by the indexing model from the issue text.