feat(nextjs): Support edge runtime

[lforst]

Ref: #6120
Ref: #4206

This PR allows users to call Sentry API inside Edge Runtime code (i.e. middleware and edge routes) to capture errors and transactions. The errors are still very barebones and we have no way of source mapping yet (we don't even know if it is possible).

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	19.84 KB (0%)
@sentry/browser - ES5 CDN Bundle (minified)	61.46 KB (0%)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.62 KB (+0.02% 🔺)
@sentry/browser - ES6 CDN Bundle (minified)	55 KB (0%)
@sentry/browser - Webpack (gzipped + minified)	20.38 KB (0%)
@sentry/browser - Webpack (minified)	66.55 KB (0%)
@sentry/react - Webpack (gzipped + minified)	20.4 KB (0%)
@sentry/nextjs Client - Webpack (gzipped + minified)	47.63 KB (0%)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	26.82 KB (+0.02% 🔺)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	25.25 KB (-0.01% 🔽)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	42.95 KB (-0.43% 🔽)
@sentry/replay - Webpack (gzipped + minified)	38.33 KB (-0.01% 🔽)

[lforst]

Okay, this is impossible to integration test because the edge code runs in some sort of sandbox which nock can't get to. I tested this extensively manually and everything should work. I will add proper E2E tests after #6746 is merged.

[AbhiPrasad]

Can we split this up into two parts?

1. where we only add the new edge client, event builder, and transport (and include it's necessary unit tests)
2. where we add the multiplexer that hooks everything up

This allows us to examine both changes in isolation, hopefully also makes it easier to review things and revert if needed.

We can leave this PR open as reference.

[lforst]

Superseded by #6752 and #6753