docs(react testing): Update testing docs to demo nested route fields

[ryan953]

This documents some new nested-route fields that were added in getsentry/sentry#100481

---

Note

Extend RTL testing docs with outlet context configuration and nested routes examples, plus a clarified route param section.

• Docs (Using React Testing Library):
  • Route Param Values: Add a dedicated heading and example clarifying use of route for useParams().
  • Outlet Context: Document passing initialRouterConfig.outletContext and consuming via useOutletContext().
  • Nested Routes:
    • Show configuring an in-memory route tree via initialRouterConfig.children.
    • Add wrapper Outlet with typed context and custom hook, plus examples for index and param child routes.

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Project	Deployment	Preview	Comments	Updated (UTC)
develop-docs	Ready	Preview	Comment	Sep 30, 2025 5:27pm

1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
sentry-docs	Ignored	Preview		Sep 30, 2025 5:27pm

[evanpurkhiser]

We should suggest they use a typed hook no? These return unknown.

Really they should be typed as

interface OutletContext {
  id: string
}

export function useWhateverOutletContext() {
  return useOutletContext<OutletContext>();
}

export function MyParentView() {
  return <Outlet id="whatever" />
}

[ryan953]

ah yeah. i can add that in so it's most copy+pasteable