runtime: implement WASM-GC

[mihaiav]

Go applications compiled to WASM with the browser as target are quite inefficient and large. Both the download payload and performance could be improved by implementing support for WASM-GC.

Chrome recently enabled WASM-GC
https://developer.chrome.com/blog/wasmgc/

[dominictobias]

Another good article: https://v8.dev/blog/wasm-gc-porting

[xushiwei]

This is what I want most in future Go version iterations.

[syrusakbary]

Once Go ships with Wasm-GC support, the binaries produced should be super small... eager to see how the Go team progresses on this!

[ianlancetaylor]

CC @golang/wasm

[johanbrandhorst]

After looking briefly at various articles about this, I expect this will be an enormous amount of work, almost comparable to writing an entirely separate compiler. There would have to be special cases at many levels within the compiler. I would also love to see this, but I think it will be hard without considerable effort.