Update Edge Runtime (vercel#38862)

This PR updates the Edge Runtime to use a new version that loads dependencies differently. This addresses vercel#38766 so `instanceof` works as expected.

It involved a few code changes, mostly regarding to types. The most important change is that the `Runner` function in the sandbox doesn't take a `ReadableStream` as `body` anymore since this implies creating the instance on "node land" and makes the runtime `fetch` function not to be able to compare with `ReadableStream` using `instanceof`.  Instead we introduce a "clonable body" abstraction that allows to create the `ReadableStream` from `Readable` by using the edge runtime primitive which would hold the correct prototype.

Also, this PR changes the way we pre-compile the Edge Runtime to adapt it to the new version.

Author: javivelasco

package.json

@@ -56,7 +56,7 @@
     "@babel/plugin-proposal-object-rest-spread": "7.14.7",
     "@babel/preset-flow": "7.14.5",
     "@babel/preset-react": "7.14.5",
-    "@edge-runtime/jest-environment": "1.1.0-beta.11",
+    "@edge-runtime/jest-environment": "1.1.0-beta.17",
     "@fullhuman/postcss-purgecss": "1.3.0",
     "@mdx-js/loader": "0.18.0",
     "@next/bundle-analyzer": "workspace:*",