### What?
When accessing `params` on a `RootLayout`, while also using parallel
routes, two potential errors would occur:
- A `Warning: React.createElement: type is invalid` error when
attempting to render a `NotFound` component that doesn't exist
- A `TypeError: Cannot read properties of undefined` error when
attempting to access params in the root layout.
### Why?
`createComponentTree` will render a duplicate `RootLayout` (to ensure
the `notFound()` fallback in unmatched parallel slots have a
`NotFoundBoundary` to catch them) but it currently doesn't ensure a
`NotFound` component exists nor does it forward `params` to the layout.
### How?
This forwards the params to the `RootLayout` and doesn't render a
`NotFoundComponent` if one doesn't exist. This replaces a few `any`
types with more sound types that would have helped catch these mistakes.
There's still a lot more typing that needs to be done (left a comment
below with some additional details) but I opted to make the minimal
changes related to this issue.
Longer term we should remove this duplicate `RootLayout` (see #60220)
which will require special UI to show unmatched slots (similar to the
error overlay, but less harsh)
Closes NEXT-1909
Fixes#59711