Launch both OpenLEADR VTN (top node) and VEN (end node) using Docker for development

(June 3, 2022) Let's explore using OpenLEADR to set up a virtual OpenADR network on a local Docker installation. The result will let us edit both the OpenLEADR source code, as well as both VTN and VEN nodes, automatically reloading both VTN and VEN when any files are changed.