DeclarationBuilder constructor Null safety

1. macro_builder
2. definition
3. DeclarationBuilder
4. DeclarationBuilder constructor

DeclarationBuilder class

1. Constructors
2. DeclarationBuilder
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. addToLibrary
8. noSuchMethod
9. toString
10. typeDeclarationOf
11. Operators
12. operator ==