Debounce stack updates / only run once per stack (instead of once per window event) / only update if indicator props change

**To reproduce**

Create a stack of 2 or more windows and execute:

```sh
yabai -m space --padding rel:25:25:25:25
yabai -m space --padding rel:25:25:25:25
```

 Indicators will update twice, the 2nd time unnecessarily, since neither their position nor any other property has changed.