BluetoothRemoteGATTService：isPrimary 属性
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
BluetoothGATTService.isPrimary 只读属性返回指示当前服务是否为主服务的布尔值。如果一个服务不是主服务，则为次级服务。