Function sleepWhile

sleepWhile(predicate: () => boolean, checkInterval?: Interval): Promise<void>
Delays until predicate returns true. Can be useful for synchronising with other async activities.
```
// Delay until 'count' reaches 5
await sleepWhile(() => count >= 5, 100);
```
Parameters
- predicate: () => boolean
- checkInterval: Interval = 100
Returns Promise<void>