feat: export function to bundle edge functions

[jackiewmacharia]

Summary

• Fixes https://github.com/netlify/pillar-runtime/issues/299

• Exports a runCoreStep function to be used by CLI to bundle edge functions when ntl deploy is called without the --build flag so file changes still reflect.

Usage:

const runCoreStepPromise = import('@netlify/build')

const bundleEdgeFunctions = async (options) => {
  const { runCoreSteps } = await runCoreStepPromise
  await runCoreSteps(['edge_functions_bundling'], Object.assign(options, { buffer: true }))
}

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[eduardoboucas]

I left a few suggestions, but this looks great in general.

We need some tests before we can merge this, though. I'm happy to help with those if you want!

[jackiewmacharia]

I've resolved the comments and updated tests.

[eduardoboucas]

This is looking great! I left a minor comment, but otherwise I think this is good to go.

[eduardoboucas]

🔥 🔥 🔥