NERtcAudioRecordingQuality constructor Null safety

1. nertc
2. nertc
3. NERtcAudioRecordingQuality
4. NERtcAudioRecordingQuality constructor

NERtcAudioRecordingQuality class

1. Constructors
2. NERtcAudioRecordingQuality
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. high
13. low
14. medium