Add maven goal to inject project properties for minikube docker-env

[loosebazooka]

Add a goal for minikube-maven-plugin to parse the result of minikube docker-env into maven project properties.

<execution>
  <id>read-minikube-docker-env</id>
  <goals>
    <goal>docker-env</goal>
  </goals>
</execution>

should read and inject the following into the project's properties

minikubeDockerEnv.DOCKER_TLS_VERIFY
minikubeDockerEnv.DOCKER_HOST
minikubeDockerEnv.DOCKER_CERT_PATH
minikubeDockerEnv.DOCKER_API_VERSION

Any plugin then interacting with a docker daemon can use these values directly in their configuration.