Docs: Improve and add new parallel routes examples

[delbaoliveira]

Continuing from: #60806

• Update conditional routes example to render dashboard pages based on user's role (rather than checking if the user is logged in)
• Add tab group example to allow each slot to be navigated independently.
• Expand the modal example to show full implementation
  • Opening the modal
  • Closing the modal
• Add catch-all slots example

Please merge after the diagrams PR: https://github.com/vercel/front/pull/28770

[ztanner]

One use-case that might be worth documenting is catch-all slots. ie, you could have a sidebar that matches all sub-paths, rather than falling back to default, with @sidebar/[...catchAll]/page.tsx.

[github-actions]

All broken links are now fixed, thank you!

[delbaoliveira]

Converting the PR back to draft as we’re currently clarifying behaviour for […catchAll] and use cases for conditional routes.