Add OG Image and share button for the contributors page

[FelixMalfait]

We recently shipped the contributors page: #3745

It would be nice to have OG images which people can share on socials.

We will use Vercel OG which we will deploy on Cloudfare: https://developers.cloudflare.com/pages/functions/plugins/vercel-og/

This ticket should be split in three parts:

• Create OG generator code (probably has to be a new package unfortunately, I don't see where we could put it - check Cloudflare link above for instructions)
• Adding OG metadata to contributor page
• Add share buttons on contributor page (we could also give contributors something they can embed in the Github README)