Use configuration input struct (#645)

As we will be passing more flags to configure
 local agents, we need a more flexible type

client/cmd/login.go

@@ -38,7 +38,12 @@ var loginCmd = &cobra.Command{
 				return err
 			}
 
-			config, err := internal.GetConfig(managementURL, adminURL, configPath, preSharedKey)
+			config, err := internal.GetConfig(internal.ConfigInput{
+				ManagementURL: managementURL,
+				AdminURL:      adminURL,
+				ConfigPath:    configPath,
+				PreSharedKey:  &preSharedKey,
+			})
 			if err != nil {
 				return fmt.Errorf("get config file: %v", err)
 			}