Allow stepping through disassembly

[danthe1st]

What it does

This PR allows stepping through the bytecode of disassembled classes in the class file editor.

This is just an unfinished prototype but I wanted to create a (draft) PR early to be able to get feedback and show the basic approach.

This depends on another PR in jdt.ui (eclipse-jdt/eclipse.jdt.ui#2708)

@SougandhS Since you have worked on similar things recently, I think you might be interested in that.

TODO

• ensure the relevant instruction is unselected/the highlighting is removed when no longer stepping through that class
• Ensure that editors aren't duplicated (?)

How to test

• Start Eclipse with this change as well as this patch
• Step through some code that steps into libraries without a source attachment
• It automatically jumps to the relevant bytecode instruction(s) corresponding to the stack frame
• Stepping through normal (non-library) classes and library classes with source attachments should still work

Author checklist

• I have thoroughly tested my changes
  • automated tests are still missing
• The change is following the coding conventions
• I have signed the Eclipse Contributor Agreement (ECA)