video property Null safety

1. volc_engine_rtc
2. bytertc_video_defines
3. PublicStreaming
4. video property

PublicStreaming class

1. Constructors
2. PublicStreaming
3. Properties
4. audio
5. hashCode
6. layout
7. roomId
8. runtimeType
9. video
10. Methods
11. noSuchMethod
12. toMap
13. toString
14. Operators
15. operator ==