add another helper method to rented instance data class

app/src/main/java/eu/m724/vastapp/vastai/data/RentedInstance.kt

@@ -73,6 +73,14 @@ data class RentedInstance(
         }
     }
 
+    /**
+     * gpu model or label if set
+     * @return instance name
+     */
+    fun getName(): String {
+        return label ?: instance.machine.gpu.model
+    }
+
     /**
      * returns whether the instance is running
      * this is true also if the instance is stopping