Split off the DockerClientFactory from this library

Most times I play with other Docker/Java libraries than TestContainers I end up in a world of dependency or configuration hell. It seems like one of the biggest reasons for this is this library's DockerClientFactory class, which does a really excellent job of inspecting the environment and choosing the best way of running Docker on the local machine with very little user intervention.

This is particularly instrumental when trying to convince other users to adopt Docker-based unit testing—if it doesn't "just work" (as it does!), skeptical developers are prone to reject the whole thing.

Therefore, I think that this class and its supporting cast should perhaps be split off into a separate package or merged upstream so that more people and projects can benefit this most commendable work. I know I'd certainly use it!

Empieza leyendo core/src/main/java/org/testcontainers/DockerClientFactory.java e identificando las clases de apoyo implicadas en la inspección del entorno y la selección del runtime de Docker. El issue propone separar esta funcionalidad en su propio package o integrarla upstream, así que primero aclara el límite de extracción y el objetivo de integración; se considerará completado cuando la funcionalidad resultante pueda beneficiar a otros proyectos Docker/Java sin los conflictos actuales de dependencias o configuración.