networker skeleton

worker: networker skeleton

This RP is a skeleton for the future networker based on StringsWorker
When you're using some other code as a template, please clean it up before proposing, unless you have questions to ask how to implement it. This whole test is not needed. You need another test that checks after starting the worker and pre-loading some networks (so that MachineNetworkInfo will return some), it generates the scripts to run that configure the NICs, possibly mocking the actual script execution.