Revamp importing to enable bumping Undici, and fixing instanceof tests within the edge runtime

[javivelasco]

This is a big iteration on how the @edge-runtime/* suite of packages work, done specifically to bump undici as a dependency.
Some context: we wanted to add WebSocket support for the edge-light runtime, and that requires bumping Undici. Unfortunately, the mechanism we used to import it previously didn't work anymore, as it uses worker_threads.
Thankfully, we also had a great idea on how to fix instanceof tests so we can avoid using unnecessary polyfills and share Uint8Arrays between the main Node.js VM and the VM we create for the edge-light runtime.
Previously, the following code didn't work:

const vm = new EdgeVM();
vm.context.MY_BINARY_ARRAY = new Uint8Array([1,2,3]);
assert(vm.evaluate(`MY_BINARY_ARRAY instanceof Uint8Array`));
assert(vm.evaluate(`MY_BINARY_ARRAY instanceof Object`));

// If the previous statements were correct, this failed:
assert(vm.evaluate(`{} instanceof Object`));
vm.context.MY_OBJ = {};
assert(vm.evaluate(`MY_OBJ instanceof Object`))

This is due to the fact that every V8 VM has its own Object, RegExp, Uint8Array (etc) classes. We fixed it now, and objects created outside of the VM will now be instanceof the classes from inside the VM.
This little change means that instead of loading modules within the VM, we can load them in the main Node.js program, and everything will work as intended: so we can upgrade Undici!
Since we still support older Node.js versions, we need to polyfill some stuff, which requires special handling for importing things. Eventually I believe we will be able to drop them.
I also didn't do any conditional logic of imports yet. I believe we can do that and offload to the native implementations when possible (like TextEncoder and TextDecoder, or even use the native undici implementation that exist for newer versions)
More noteworthy changes:

1. I extracted the tests from @edge-runtime/primitives into a new module called @edge-runtime/integration-tests, which, surprisingly, only runs integration tests. This fixes the circular dependency of primitives -> jest-environment -> primitives, which was annoying. Primitives also requires to build before running the tests so it's not like we're making a worse iteration speed. These tests are using @edge-runtime/ponyfill so they actually being tested both using the @edge-runtime/jest-environment and the standard Node.js environment using the same code!
2. Importing @edge-runtime/primitives/* is discouraged. Since there is a mandatory order of imports, and we don't use the standard require to import the dependencies, for good and bad.
3. Bumping undici means that we now have the getSetCookies function. We still support the getAll to avoid breaking changse, but internally it uses getSetCookies.
4. The structuredClone polyfill now supports ReadableStream (as mentioned in MDN), because Undici uses it.
5. We expose WebSocket constructor now! (resolves EC-617)

closes #265

[changeset-bot]

🦋 Changeset detected

Latest commit: 34e540b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 11 packages

Name	Type
@edge-runtime/jest-environment	Minor
@edge-runtime/jest-expect	Minor
@edge-runtime/node-utils	Minor
@edge-runtime/primitives	Minor
@edge-runtime/user-agent	Minor
@edge-runtime/ponyfill	Minor
@edge-runtime/cookies	Minor
edge-runtime	Minor
@edge-runtime/format	Minor
@edge-runtime/types	Minor
@edge-runtime/vm	Minor

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Name	Status	Preview	Comments	Updated (UTC)
edge-runtime	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 2, 2023 11:25am

[nuta]

Nice! 💯 Left some nitpicks for now. Will look at the details later.