azureclient: Add MicrosoftGraphEndpoint to AROEnvironment

The Azure/go-autorest module does not define an endpoint for the
Microsoft Graph API [1] so define it ourselves for now.

[1] Azure/go-autorest#585

pkg/util/azureclient/environments.go

@@ -14,6 +14,7 @@ import (
 type AROEnvironment struct {
 	azure.Environment
 	ActualCloudName          string
+	MicrosoftGraphEndpoint   string // Work around https://github.com/Azure/go-autorest/issues/585
 	GenevaMonitoringEndpoint string
 	AppSuffix                string
 }
@@ -23,6 +24,7 @@ var (
 	PublicCloud = AROEnvironment{
 		Environment:              azure.PublicCloud,
 		ActualCloudName:          "AzureCloud",
+		MicrosoftGraphEndpoint:   "https://graph.microsoft.com",
 		GenevaMonitoringEndpoint: "https://gcs.prod.monitoring.core.windows.net/",
 		AppSuffix:                "aro.azure.com",
 	}
@@ -31,6 +33,7 @@ var (
 	USGovernmentCloud = AROEnvironment{
 		Environment:              azure.USGovernmentCloud,
 		ActualCloudName:          "AzureUSGovernment",
+		MicrosoftGraphEndpoint:   "https://graph.microsoft.us",
 		GenevaMonitoringEndpoint: "https://gcs.monitoring.core.usgovcloudapi.net/",
 		AppSuffix:                "aro.azure.us",
 	}