Add rewrite functionality to BECR

Enhance BECR to perform rewrites / refactoring

References and ideas
* https://comby.dev/
* Multifile replacement
* Will use ASTRewrite as part of Eclipse JDT

* Callouts for replacements (0.6.0)
* For example, each time a match is found, call a method which the user can define
* This would allow custom refactoring to be accomplished with BECR handling the actual details, minimizing the custom code required
* Could use Eclipse's binding information to verify the type matches what's expected

* Ability to add imports
* Ability to track changes so can put into report or use to change another file (such as changing one file based on the matches in another file)