Refactor Scala IR to Java

[Akirathan]

This is an umbrella issue to track progress on refactoring Scala IR in runtime-parser to Java.

The initial PR that introduced the annotation processor is #11770

The initial issue is #11498

Motivation

• Ultimate goal is to replace all Scala code in runtime-parser by Java
• Remove boilerplate Scala code.
  • The old IR case classes had to manually implement, e.g., copy, duplicate and mapExpressions methods.
  • Tedious and error prone.
• All the repetitive code of methods like copy, mapExpressions, children, etc. shall be generated by an annotation processor.
• Will unblock further work on migration towards mini IR passes
  • To continue with mini IR passes, we observed that having withNewChildren (or setNewChildren) method would be very useful, so that mini IR passes can traverse every IR node.
  • Once code for IR nodes is generated, implementing new methods on every IR node will be straightforward.

Work that has already been done

• Refactor Name Scala IR to Java #14244
• Refactor Definition Scala IR to Java #14252
• Refactor Method IR to Java #14086
• Refactor Foreign IR to Java #13943
• Refactor Function IR to Java #13037
• Refactor usage of Java IR types #13788
• Refactor Case IR to Java #13004
• Refactor more IR Scala case classes to Java #12474
• Replace more IR Scala case classes with Java interfaces #12211