NERtcLogLevel constructor Null safety

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

NERtcLogLevel class

1. Constructors
2. NERtcLogLevel
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. debug
13. detail_info
14. error
15. fatal
16. info
17. verbose
18. warning