w3s.link: support application/vnd.ipld.car

[lidel]

Users should be able to fetch a CAR by explicitly requesting it via ?format=car or Accept: application/vnd.ipld.car

Ref.

• https://www.iana.org/assignments/media-types/application/vnd.ipld.car
• https://docs.ipfs.tech/reference/http/gateway/#example-fetching-an-entire-dag-as-a-car-stream-from-a-public-gateway