gateway multiple domains

Change how the PowerBI service looks at gateways and allow multiple gateways to be shown if the server name matches more than one gateway. Our use case is we have separate domains for DEV and PROD, but our DNS names are the same we do not have to change configuration when moving items in environments. Today the only way to leverage a DEV/QA gateway is to name the Server name different and then we have to match that in the PBIX file. That causes that we have to change out PBIX in each environment thus adding risk to a change not tested prior in DEV. Each gateway would have the same server name, but internally when going through the gateway we would point to different data sources.