Add section to docs on how to debug StarlingMonkey application

[andreiltd]

Our developer guide section on debugging is currently empty: https://bytecodealliance.github.io/StarlingMonkey/developer/debugging.html

cc: @squillace

[squillace]

Ok! First, I've got debugging working to resolve https://github.com/bytecodealliance/sample-wasi-http-js/issues/4, which is the perfect example to use to write this document, here.