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. toString
13. Operators
14. operator ==