Add the ability to add more than a single dashboard to the homepage

[stefanobartoletti]

Feature request

I think it would be useful to be able to pin more than a single dashboard to the home page, maybe by using some tabs, like in the screenshots.

As a bonus, the filtered data could be shared among these tabs.

Also, it would be nice to be able to also hide the top boxes, if not needed.

Overall, a more customizable homepage would be great

Debug info

- [ ] PostHog Cloud, Debug information: [please copy/paste from https://us.posthog.com/settings/project-details#variables]
- [ ] PostHog Hobby self-hosted with `docker compose`, version/commit: [please provide]
- [ ] PostHog self-hosted with Kubernetes (deprecated, see [`Sunsetting Kubernetes support`](https://posthog.com/blog/sunsetting-helm-support-posthog)), version/commit: [please provide]