Add Typescript types for all app-router component file conventions

[kpervin]

Goals

Add Typescript types for new app-router file conventions.

Non-Goals

No response

Background

Previously for the pages router we had type exports for getServerSideProps, NextPage, etc. For the new file conventions, having typescript types for the functions would be ideal.

Proposal

For the new app router, having types for layout.tsx, page.tsx, etc would be optimal as we would be able to know about using:

• layout props: { children: ReactNode; params?: Record<string, string> }
• page props: { params?: Record<string, string>; searchParams?: Record<string, string> }

and so on. Having these in typescript types reduces the need to go to the documentation.

[Netail]

As we now also have generated types for next/link (typedRoutes), it would also be nice to automatically have params generated in these types