Alert length vs Cool down 
**Describe the bug**
Problem configuring homekit automations based on camera motion detected or motion stops detecting events.
The events are not lasting long enough. I would expect the triggered state to remain unchanged during the cool down period. or at least be longer than the check interval.
If current behavior is by design, is it possible to include the alert length in the configuration where it could be user defined.

**To Reproduce**
Steps to reproduce the behavior:
1. Constant behavior that motion state will revert to false 5 sec after event

**Expected behavior**
Triggered motion events remain true during cool down period

**Last Working Version**
2.1.0 
Was working prior to number of alert fixes for motion. or the addition of the fixed Alert_length
Include with your bug report this version info:
```
node --12.18.0
homebridge --1.1.0
```

Make sure you have the latest LTS from https://nodejs.org
and the latest packages: `npm upgrade -g homebridge homebridge-nest-cam`

seems like it may be tied to this section of code
  triggerMotion(accessory: PlatformAccessory): void {
    const self = this; // eslint-disable-line @typescript-eslint/no-this-alias
    this.setMotion(accessory, true);
    this.motionDetected = true;
    setTimeout(async function () {
      self.setMotion(accessory, false);
    }, ALERT_LENGTH);

    setTimeout(async function () {
      self.motionDetected = false;
    }, this.alertCooldown);
  }