https://developers.weixin.qq.com/miniprogram/dev/api/device/bluetooth-ble/wx.getBLEDeviceRSSI.html

加这样一个函数很麻烦，是否可以在监听特征值变化的回调中加一项返回值，返回信号强度

wx.onBLECharacteristicValueChange(function listener)

https://developers.weixin.qq.com/miniprogram/dev/api/device/bluetooth-ble/wx.onBLECharacteristicValueChange.html

即在这个api中添加