Add compileString function

[Vurv78]

I was going to add a runString function a while back, but it was scrapped for concerns about invoking the compiler so many times to intentionally cause lag. Having a compileString function instead would allow us to ratelimit it more strictly since you could re-use the output function.

Would need to address potential DOS attacks with specially crafted code to make the compiler lag.. I think just adding ops per byte, plus per token in tokenizer should be enough.

RFC

Could this lock us into anything backwards compatibility wise?