Replace default class file editor with one crafted by BytecodeOutline.

Following on from [the addition of BCO into Eclipse](https://github.com/eclipse-jdt/eclipse.jdt.ui/issues/364), [the original suggestion from 2018](https://bugs.eclipse.org/bugs/show_bug.cgi?id=540436) suggested improvements to the default class file editor.

As a user, when reading a .class file, it can be difficult to understand the bytecode without proper syntax highlighting and/or colour coding. In order to improve the readability of class files in the default class file editor, the following changes are proposed:

- Implement syntax highlighting and color coding to highlight keywords and identifiers, similar to the Java editor.
- Add hovers to display more information about specific bytecode instructions.
- Improve the overall appearance of the disassembled source by adding outline and navigation features.

This is something I am happy to work on, but any suggestions are welcome.
I would like to thank @iloveeclipse as well for their hard work integrating BCO into Eclipse. 🙏 🙇‍♀️