Adds the component which receives the messages from client and a module which enabled on a virtual host will start advertising the component. When clients discover the component they will send message to the component with the name of the room where the dominant speaker event happen.

When combined with mod_muc_poltergeist mod_muc_call allows
for enabling call features using a proper ext_events.lib.lua
implementation. By default when the module is configured only
stub implementations are used for ext_events.lib.lua as these
are unique between deployments.