Improve the Next.js Docker image

[dunglas]

The Next.js Docker image should be improved by using the official image:

• https://github.com/vercel/next.js/tree/canary/examples/with-docker-compose
• https://github.com/vercel/next.js/tree/canary/examples/with-docker-multi-env
• https://github.com/vercel/next.js/tree/canary/examples/with-docker