Fix: cant start route with @ within Layout Routes (#8699)

[theostavrides]

Fixes bug #8699

When a route is nested within a layout route, it wont render routes starting with an '@' symbol:

<Routes>
    <Route element={<Layout />}>
        <Route path=":id" element={<Chat />} />
    </Route>
</Routes>

Note that the router works correctly when the parent is NOT a layout route (i.e. has a path defined), or is at the root level:

    <Router>
      <Routes>
        <Route path=":id" element={'works with /@tom'}/>
        <Route path="nested">
          <Route path=":id" element={'works with /nested/@tom'}/>
        </Route>
      </Routes>
    </Router>

[remix-cla-bot]

Hi @theostavrides,

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Thanks!

- The Remix team

[remix-cla-bot]

Thank you for signing the Contributor License Agreement. Let's get this merged! 🥳

[knpwrs]

This would also fix remix-run/remix#2012

[kgamecarter]

also fix remix-run/remix#846

[chaance]

@theostavrides I'd love to merge this. Would you mind resolving the merge conflicts and updating your branch?

It's actually simple, we just reorganized our file structure a bit and the updated code is now in react-router/lib/router.ts. Thanks a ton!

[theostavrides]

@chaance Would be happy to. I'll get on it tomorrow