Add the activeParticipats event to the notification service RN+Android

[graduad]

Add following events to the notification service:

• active participants

Only RN and Android work. iOS to be done in separate ticket.

[mohsindlb]

Please add following events also

• participantJoined
• participantLeft

[graduad]

@mohsindlb, we have planed this already under a different ticket. Please see: https://github.com/DolbyIO/comms-sdk-react-native/issues/75

[asadumair]

for ios and also for the listener ?

[graduad]

Implemented in 3.8.0 Beta 1

@asadumair iOS is implemented as well, but as per first message, it has been tracked in a different ticket.