Change the way muting servers works

Make it sowhen you mute the server, each cathegory can be unmuted separately. For example, I wannna mute the server for the night, but I still want to get notifications from mod and important channels/cathegories, so I'll just mute the server then go to the channel/cathegory I need and unmute it. This would be way easier than just muting everything by hand, so one cathegory can be left unmuted.