ICustomMessageButton constructor Null safety

1. nyxx
2. nyxx
3. ICustomMessageButton
4. ICustomMessageButton constructor

ICustomMessageButton class

1. Constructors
2. ICustomMessageButton
3. Properties
4. customId
5. disabled
6. emoji
7. hashCode
8. label
9. runtimeType
10. style
11. type
12. Methods
13. noSuchMethod
14. toString
15. Operators
16. operator ==