break: use a docker image type for modules

[mdelapenya]

What does this PR do?

It adds a new type alias for string to represent Docker image names, which will be used in the signature of all the Run functions in the modules.

All calls to Run with an untyped string will not break, but users of the lib passing a typed string will have to change it to a testcontainers.DockerImage.

Why is it important?

It will allow providing support for the compatible-for feature in testcontainers-java, among other Docker image validations.