fix: Fix av moderation enable-disable sequence.

When you enable and then disable av-moderation just the audio moderation is disabled and video moderation disabling is not signalled to moderated clients.

resources/prosody-plugins/mod_av_moderation_component.lua

                         room.av_moderation = {};
                         room.av_moderation_actors = {};
                     end
+                    room.av_moderation[mediaType] = {};
                     room.av_moderation_actors[mediaType] = occupant.nick;
                 end
             else