[WIP] Prerender stats pages for faster production builds

[Ked57]

This PR is motivated by the fact that statistics can be time intensive to process and don't need to be realtime accurate.

NextJS allows us to pre-render a page with data fetched at build time, data is then refetched every X seconds (I set 5 minutes in this case). This is a nice solution to make stats pages blazing fast 🚀

@hgwood: FYI since it's the nextjs server that executes the fetching this is going to require access to hasura admin secret in production

[hgwood]

I've added the admin secret of the production instance of Hasura to the environment variables of the production instance of the app (as HASURA_ADMIN_SECRET to match the code in the PR).

[Ked57]

I've added the admin secret of the production instance of Hasura to the environment variables of the production instance of the app (as HASURA_ADMIN_SECRET to match the code in the PR).

Thanks a lot 🙏

[Ked57]

This works well in production build mode but freezes the dev build. The problem that this PR would help solve is already being well mitigated by #84. I will not merge this for now until I find a solution to the dev build freeze problem