Uniform website build and deployment across projects

[vasco-santos]

We currently maintain many projects with websites: nft.storage, web3.storage, nftstorage.link ...

We should uniform them all for two reasons:

• reduce maintenance burden of everything being setup differently
• move towards a better environment setup, where all build env vars and release process is in github actions

Part of this was implemented on https://github.com/nftstorage/nft.storage/pull/2101, but we still need to fully uniform the projects.

Requirements:

• Workflow stages: check, test, preview, changelog, release
• Build in CI and deployment with wrangler for staging and production
• Add to w3s and make available on web3.storage

Basically port https://github.com/web3-storage/web3.storage/blob/main/.github/workflows/website.yml to the other places :)