clean up JavacAnnotatedConstruct

model/JavacAnnotatedConstruct needs to be cleaned up.

- We need input validation on unpacking the the array for repeated annotations.

- There is lots of code duplication

- The functionality should be moved to preferably an abstract base type to Symbol and Type. If that introduced performance penalty in general the file can be refactored, most of the methods can be moved to Symbol or Type and a common interface JCAnnoConstruct can be introduced. In 9 we can then move the rest of this code into default methods in JCAnnoConstruct.