feat(nextjs): added webpack treeshaking flags as config

[logaretm]

This PR updates the Sentry Next.js integration to improve tree-shaking configuration and add new options for finer control over what SDK code is included in the final bundle.

The most significant changes are:

• Added several new tree-shaking flags for better user DX.

Closes #18417

[linear[bot]]

JS-1222 Add treeshaking option for webpack

[github-actions[bot]]

size-limit report 📦

Path	Size	% Change	Change
@sentry/browser	24.81 kB	-	-
@sentry/browser - with treeshaking flags	23.3 kB	-	-
@sentry/browser (incl. Tracing)	41.55 kB	-	-
@sentry/browser (incl. Tracing, Profiling)	46.16 kB	-	-
@sentry/browser (incl. Tracing, Replay)	79.97 kB	-	-
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	69.7 kB	+0.01%	+1 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)	84.65 kB	-	-
@sentry/browser (incl. Tracing, Replay, Feedback)	96.89 kB	-	-
@sentry/browser (incl. Feedback)	41.52 kB	-	-
@sentry/browser (incl. sendFeedback)	29.49 kB	+0.01%	+1 B 🔺
@sentry/browser (incl. FeedbackAsync)	34.48 kB	+0.01%	+1 B 🔺
@sentry/react	26.52 kB	-	-
@sentry/react (incl. Tracing)	43.76 kB	-	-
@sentry/vue	29.27 kB	-	-
@sentry/vue (incl. Tracing)	43.36 kB	-	-
@sentry/svelte	24.82 kB	-	-
CDN Bundle	27.23 kB	-	-
CDN Bundle (incl. Tracing)	42.22 kB	-	-
CDN Bundle (incl. Tracing, Replay)	78.75 kB	+0.01%	+1 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)	84.2 kB	-	-
CDN Bundle - uncompressed	80.02 kB	-	-
CDN Bundle (incl. Tracing) - uncompressed	125.37 kB	-	-
CDN Bundle (incl. Tracing, Replay) - uncompressed	241.41 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	254.17 kB	-	-
@sentry/nextjs (client)	45.98 kB	-	-
@sentry/sveltekit (client)	41.93 kB	-	-
@sentry/node-core	51.6 kB	-	-
@sentry/node	161.48 kB	+0.01%	+1 B 🔺
@sentry/node - without tracing	93.03 kB	-	-
@sentry/aws-serverless	108.54 kB	-0.01%	-1 B 🔽

View base workflow run

[chargome]

@logaretm make sure to add a section in the changelog for this 🙏