Allow specifying full image in KafkaContainer

[s4nk]

At the moment KafkaContainer only allows to specify the Confluent platform version (which under the hood translates into a version of the "confluentinc/cp-kafka" image). In org.testcontainers.containers.KafkaContainer the two constructors used by com.dimafeng.testcontainers.KafkaContainer are now deprecated, and the only one available is public KafkaContainer(final DockerImageName dockerImageName). An equivalent change and deprecation could be made in com.dimafeng.testcontainers.KafkaContainer.