Add music functionality to the bot

[DocSystem]

Related to #2

Add music functionality to the bot.

• Add discord-music-player dependency: Update package.json to include discord-music-player dependency.
• Add play music command: Create commands/playmusic.js to handle playing music in a voice channel.
• Add pause music command: Create commands/pausemusic.js to handle pausing the currently playing music.
• Add skip music command: Create commands/skipmusic.js to handle skipping the currently playing music.
• Add queue music command: Create commands/queuemusic.js to handle showing the current music queue.

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For more details, open the Copilot Workspace session.