DockerWrapper: a wrapper for using nerdctl with the Jenkins docker-workflow-plugin on Windows

It creates a docker executable that acts as a passthrough for nerdctl except for when invoked as docker --version, at which point it injects a higher version number into the output so that the docker-workflow-plugin will use the working codepath for Windows builds.

See jenkinsci/docker-workflow-plugin#370 for more background and an upstream patch that should also work around it.