Expose sat via subo

[flaki]

Making it easier to use sat and bundling it with subo would be really useful for the developer experience. Having something like subo exec wasm-runnable.wasm which would pass the runnable to sat would be great.

---

Fun fact, way-back-when Vercel/Zeit/Now got nagged day & night about making their cloud functions available in a local dev environment, which led to micro(-dev), we should be following in their footsteps and make running single runnables a breeze in dev mode, separately from atmo as a whole.