Add Tunneling to existing quick start guides

[inventarSarah]

SDK

Javascript SDK

Description

Quick start guides should have a step about tunneling (where relevant)

Guides to update:

• Angular
• Nuxt
• React
• Svelte

Suggested Solution

Should be similar to what we have in our Next.js guide: https://docs.sentry.io/platforms/javascript/guides/nextjs/manual-setup/#step-5-avoid-ad-blockers-with-tunneling-optional

[inventarSarah]

to discuss:

• we currently only have tunneling in the manual setup (next.js) and not the wizard (check if the wizard mentions this; should it be in both?)
• in some cases, setting up tunneling is complex (eg SvelteKit) and we link to a different page
  • while this is not ideal, I think this is better than just linking to it from the next steps (users may encounter problems while following the quick start guide so "next steps" may already be too late)