[Bug]: Camera battery level never updates.
### What happened?

The battery level of cameras like the 2C never get updated.  The battery level is pulled only once when HomeBridge is restarted and that battery level is shown in perpetuity.

Also, it would be great if you could add HomeKit's low battery warning once the level falls below a certain percent (15 maybe?).  I believe it's just a flag for the device and HomeKit handles the rest.  I think doorbells have a 'DeviceBatteryLow' property from the eufy API itself but cameras have no such property, so you'd have to do some logic instead.

### Device Type

Camera (Supported)

### Plugin Version

v2.0.x (Supported)

### HomeBridge Version

v1.4.x (Supported)

### NodeJS Version

v12 (Supported)

### Operating System

Raspbian 10+ (Supported)

### Relevant log output

```shell
N/A
```


### config

```shell
N/A
```
