Upgrade to Payload CMS v3

[Payload CMS v3](https://github.com/payloadcms/payload/releases/tag/v3.0.0) has been available for a while now.

We need to upgrade each individual app that uses Payload in this repo to the latest version of Payload to take advantage of the latest features and improvements. However from the release notes of v3 it is indicated that:
> This is a major release that includes a re-architecture of Payload from an Express + React Router SPA to the Next.js App Router + RSCs. In addition to this architectural change, we've also shipped a ton of large features, miscellaneous fixes, and DX improvements.

Will this integrate well with our apps since we are using pages router ?

Additionally here are some of the things that were discussed in the past that could be revisited once the upgrade is done:
- Migrating from the legacy [Slate Editor](https://payloadcms.com/docs/rich-text/slate) to [Rich Text](https://payloadcms.com/docs/rich-text/overview) editor.
- Allow users to create tables within the CMS (perhaps integrating with[ lexical table](https://lexical.dev/docs/packages/lexical-table)
- Using one CMS to manage content of all apps that use Payload CMS.