ParticipantEvent constructor Null safety

1. livekit_client
2. livekit_client
3. ParticipantEvent
4. ParticipantEvent constructor

ParticipantEvent class

1. Constructors
2. ParticipantEvent
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==