Updated nested-components example to use App Router

[Shruthireddy04]

This PR updates the nested-components example to use the App Router. Here are the changes that have been made:

Renamed the "pages" folder to "app" folder.
Updated the file index.tsx to page.tsx to align with App Router.
Added the layout.tsx file as part of the App Router.
Updated the components folder to align with App Router and made components folder private.
Updated package.json to use the latest version.

cc: @samcx

[ijjk]

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[samcx]

Thank you for submitting a PR!

[samcx]

@Shruthireddy04 Is there a reason why the jsx was removed with the style jsx styles?

[Shruthireddy04]

@samcx According to docs css in js can be used only in client components but here component is not performing any client operations so instead of making it client component removed jsx.

[samcx]

@Shruthireddy04 I switched it to CSS modules because there were hydration issues going on.