[Enhancement]: Provide a way to customize extra docker containers used

[vikstrous2]

Proposal

In more locked down / secured environments, it can be problematic to pull images from docker hub and run them without additional precautions.

One need is to prefix images so that they can be pulled from a docker registry other than docker hub. This is the usual mechanism for using docker image proxies, caches, etc.

Another need is to pin images to specific hashes to protect against supply chain attacks. When images are not pinned to a specific hash, an attacker with control of the docker account that hosts the images can publish a new image with the same tag that contains malicious code.

The latter issue also exists for images referenced by this repo normally, so maybe it can be solved differently from the first. Maybe images used by testcontainers can always be pinned by hash by default?

[mdelapenya]

Thanks for reporting this issue, it's concerning knowing that there are security issues with some images used here. Could you elaborate a list of them, out fix them in a PR? 🙏

Regarding the name substitution, testcontainers-java does have that mechanism, and I think we could add it here too.

I will talk internally to other maintainers to reach to a proper design + implementation.

Thanks for your time!