Add descriptions during load/refresh in PBI desktop, instead of just "Creating connection in model"

[elliott_young1]

Need to know progress of a load. Terrible user experience to wait for 20 minutes of "Creating conenction in model..." only to find it fails and hasn't even downloaded a single row of data. Need to know: If one connection is waiting on anther one, how many rows have been loaded, how long the load has been running for, the b/second, how many parallel loads/threads are running etc. Just need visibility of what the desktop app is doing after you click Close and Apply.