Enhance the api to allow .offline() when using the .import*Dependencies() methods

It would be great if I could do something like this:

Maven.resolver().loadPomFromFile("pom.xml").importRuntimeDependencies().offline().as(File.class);

But the (fluent) api doesn't permit the .offline() method for the class/interface that's returned from the .importRuntimeDependencies() methods.

For the workaround that I tried to use (but which doesn't pay attention to the offline setting), see the attached test case (v2).