Add/remove voice channels

[alex-sandro92]

Easy fix to add voice channels with separate commands.

To add voice channel:

• [p]aiemote allow_voice #!voice_channel
• [p]aiemote add_voice #!voice_channel
• [p]aiuser add_voice #!voice_channel

To remove:

• [p]aiemote remove_voice #!voice_channel
• [p]aiemote rm_voice #!voice_channel
• [p]aiuser remove_voice #!voice_channel
• [p]aiuser rm_voice #!voice_channel

[zhaobenny]

Oof, just saw this PR after I already pushed a different fix to the voice channel issue right now 😅

Thank you for your effort anyways!