ICommandRegistrable constructor Null safety

1. nyxx_commander
2. nyxx_commander
3. ICommandRegistrable
4. ICommandRegistrable constructor

ICommandRegistrable class

1. Constructors
2. ICommandRegistrable
3. Properties
4. commandEntities
5. hashCode
6. runtimeType
7. Methods
8. noSuchMethod
9. registerCommandEntity
10. toString
11. Operators
12. operator ==