Supports custom docker engine port in DockerMachineClientProviderStrategy

The port is hardcoded as ```2376``` in
https://github.com/testcontainers/testcontainers-java/blob/f113979ad5207464490cc4f19f488bb27795802c/core/src/main/java/org/testcontainers/dockerclient/DockerMachineClientProviderStrategy.java#L57

It should be parsed from the output of ```docker-machine ls```