BluetoothRemoteGATTCharacteristic：uuid 属性
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
BluetoothRemoteGATTCharacteristic.uuid 只读属性返回包含特性的 UUID 字符串，例如心率测量特性的 UUID 是 '00002a37-0000-1000-8000-00805f9b34fb'。