ConstText constructor Null safety

1. mc_gallery
2. const_text
3. ConstText
4. ConstText constructor

ConstText class

1. Constructors
2. ConstText
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static methods
12. imageOverlayTextStyle