Allow routes starting with @ in layout routes

[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>

[theostavrides]

@chaance Hey I messed up my last PR (#8700) so I made a new one.