Support for not rendering chat widgets for all data messages

[agazso]

Currently all DataMessages sent between the objects result in a rendered component. However there were discussions where sometimes there could be better UX if the DataMessage would not display a new bubble, but change the state of an existing one. With the current implementation there is no way to do it, and it would be great to cover this. For example the WakuObjectDescriptor could have a function that returns a boolean based on the message and the current state if the message needs to be displayed or not, or the onMessage could return a boolean. This is getting more interesting with the external object because here we need to decide if we want to display a chat bubble or not before the iframe is displayed and logic runs in that.

Originally from #359