NERtcAudioFocusMode constructor Null safety

1. netease_roomkit
2. netease_roomkit
3. NERtcAudioFocusMode
4. NERtcAudioFocusMode constructor

NERtcAudioFocusMode class

1. Constructors
2. NERtcAudioFocusMode
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. audioFocusGain
13. audioFocusGainTransient
14. audioFocusGainTransientExclusive
15. audioFocusGainTransientMayDuck
16. audioFocusOff