feat(vercel-edge): Add fetch instrumentation

[lforst]

Adds a WinterCGFetch integration to be used in only the vercel-edge package for now. It instruments fetch on WinterCG runtimes. We can later hoist it into a more generic package.

Disclaimer: This currently doesn't work on Vercel for unknown reasons. It works on local Next.js.

Resolves #6804

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	65.53 KB (+0.06% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	55.67 KB (+0.05% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	31.01 KB (+0.11% 🔺)
@sentry/browser - Webpack (gzipped)	21.32 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	61.99 KB (+0.04% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	29.13 KB (+0.09% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	21.26 KB (+0.09% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	195.53 KB (+0.03% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	88.38 KB (+0.07% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	63.34 KB (+0.07% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	31.85 KB (+0.12% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	65.84 KB (-0.01% 🔽)
@sentry/react - Webpack (gzipped)	21.36 KB (+0.08% 🔺)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	82.58 KB (+0.03% 🔺)
@sentry/nextjs Client - Webpack (gzipped)	48.15 KB (+0.05% 🔺)
@sentry-internal/feedback - Webpack (gzipped)	16.08 KB (0%)

[Lms24]

Nice!