Register based bytecode

[playXE]

Stack based bytecode is quite hard to maintain especially when you have to deal with iterators so I want to get register based bytecode in Starlight. We could write a DSL for generating one just like JSC:
https://github.com/WebKit/WebKit/blob/main/Source/JavaScriptCore/bytecode/BytecodeList.rb
https://github.com/WebKit/WebKit/tree/main/Source/JavaScriptCore/generator

[playXE]

Such a change will require almost full execution pipeline rewrite and probably will take about a month or more to finish but I hope it is worth it.