Support for WASM

[swankjesse]

Zipline is currently built on Kotlin/JS, which creates some complexity and limitations:

• Lots of things are built on JS runtime APIs, including setTimeout, console, and JSON
• Intermediate .js source files going from Kotlin source to QuickJS bytecode
• Zipline needs QuickJS bytecode parsing to inject .kt line numbers
• No debugger

It’d be nicer to use WASM instead of QuickJS bytecode as Zipline’s standard instruction format. We can’t do this yet as Kotlin’s WASM support is still extremely experimental. But if/when that matures we should support it and create a gentle upgrade path from QuickJS to WASM.