ref(node): Move request-data-extraction functions to@sentry/utils

[lobsterkatie]

See #5190 for a detailed description of the motivation for and main substance of this change. TL;DR, isomorphic frameworks like Nextjs need this code to live in a neutral location (rather than in the node package) so it can be used in a browser setting as well.

This is a second take on #5190, which had to be reverted because it relied on a peer dependency (cookie) which browser-only apps wouldn't have installed. Even if those code didn't use cookie, they still failed to compile because without cookie installed, @sentry/utils didn't typecheck correctly.

This fixes that problem by using cookie (and url, for node 8 compatibility) only as injected dependencies, not as direct ones. It also creates node-specific versions of the relevant functions (parseRequest, now renamed addRequestDataToEvent, and extractRequestData) which do the injection automatically. If the dependencies aren't passed (as would be the case in a browser setting, or when using the functions directly from @sentry/utils), the code about cookies no-ops, and the code about URLs uses URL, which should be defined in all modern browsers and Node 10 and above.

Other changes from the original PR:

• Now only the backwards-compatibility-preserving wrappers of the legacy code live in handlers.ts, while the legacy code itself lives in its own file. This both makes it easier to delete in the future and ensures that treeshaking algorithms which only work file-by-file (rather than function-by-function) are able to exclude that code. (Though it's being kept until v8 because it's part of the node package's public API, it's no longer used anywhere in the SDK.)
• Using DI changed the options interface for both of the functions in question, which in turn required a bit more gymnastics in terms of preserving and test backwards compatibility, specifically in the serverless package and the backwards-compatibility tests. This will make it a little harder to delete the old stuff when it comes time, but there are TODOs which hopefully will make it clear enough what needs to happen.
• There's a new CrossPlatformRequest type for use in place of ExpressRequest. A few helper functions have also been renamed to make them less Express-centric.

Ref: WEB-957

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	19.43 KB (added)
@sentry/browser - ES5 CDN Bundle (minified)	60.21 KB (added)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.24 KB (added)
@sentry/browser - ES6 CDN Bundle (minified)	53.83 KB (added)
@sentry/browser - Webpack (gzipped + minified)	20 KB (added)
@sentry/browser - Webpack (minified)	65.2 KB (added)
@sentry/react - Webpack (gzipped + minified)	20.02 KB (added)
@sentry/nextjs Client - Webpack (gzipped + minified)	44.02 KB (added)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	25.63 KB (added)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	24.16 KB (added)