Adds support for lazy loading sub-routes / components using the pattern below:

const routes [
  // ...
  {
    path: 'part1',
      handle: {
        lazyChildren: () =>
          import('./pages/SomeMoreNestedRoutes').then(
        (mod) => mod.someMoreNestedRoutes
      ),
    },
  },
]

lazyChildren is not a predefined key; it can be anything returning renderable data.

Not sure about the widespread usage of the pattern, but as it requires a recursive search inside the whole route tree, it potentially creates performance overhead.
So, added a new option [enableAsyncRouteHandlers] to the RR Tracing Integration and these checks will only run when it's set.