[FEATURE REQUEST] promise for job save and update

So we can using following syntax:

```
const test = async () => {
let job = await Job.get(id)
await job.save()
await job.update()
}
```

Start by tracing the Job.get, job.save, and job.update entry points mentioned in the example, then inspect how their current asynchronous behavior is exposed. Confirm the existing callback behavior and identify relevant tests before defining completion as support for the shown await syntax without breaking current usage.

Written by the indexing model from the issue text.