Get the enumeration of portals. This list correlates with the list of portals
on the "Portals" tab on the Pro backstage.
ArcGISPortalManager: Get a list of all your Portals
var portals = ArcGISPortalManager.Current.GetPortals();
//Make a list of all the Uris
var portalUris = portals.Select(p => p.PortalUri.ToString()).ToList();
Target Platforms: Windows 11, Windows 10
ArcGIS Pro version: 3 or higher.