@guardian/image

**Note, this will not work without the correct salt value so only usuable within
the Guardian.**

Security: use this library server-side only.

A server-side JS/Typescript library to sign and format master images so that
they can be served through our Fastly image service.

format(url: string, salt: string, profile: Profile)

url must be a valid master image URL.

salt must be kept secure. Do not use this library on the client-side.

Profile can include any properties supported by the Fastly image service. Docs
here: https://docs.fastly.com/api/imageopto/#image-api-reference.