feat: add @edge-runtime/cookies helpers

[Schniz]

This provides utilities to handle with cookie parsing & manipulating with Request/Response objects.

The code was copied from the Next.js repo, to provide these utilities to other frameworks so they can reuse this logic when they deploy to any Edge Runtime-compatible service.

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Name	Status	Preview	Updated
edge-runtime	✅ Ready (Inspect)	Visit Preview	Aug 23, 2022 at 11:18AM (UTC)

[Schniz]

discussion:

I feel like Cookies can have a better API, or at least a .commit(headers) method (or, commit(cookies, headers) function) that will make ManipulateHeadersCookies much simpler.

Maybe even

type CookiesOptions = {
  onCookieChanges(name: string, value: string, options: CookieOptions): void
};
class Cookies extends Map<string, string> {
  constructor(cookieHeader: string | null | undefined, private readonly options: CookiesOptions) {
    // ...
  }
}

🤔

[Schniz]

I'm gonna open a new PR for this