NERtcClientRole constructor Null safety

1. yunxin_roomkit
2. roomkit
3. NERtcClientRole
4. NERtcClientRole constructor

NERtcClientRole class

1. Constructors
2. NERtcClientRole
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. audience
13. broadcaster