Add benchbot to monitor and evaluate scheduling

## Feature Request

### Describe your feature request related problem:

We do not have an effective method to measure scheduling in time.

### Describe the feature you'd like:

Benchbot can run with some command after reply to some keyword in PR. we may enhance it to monitor and evaluate the impact of scheduling policy changes.

### Describe alternatives you've considered:

The result may include:
- Jitter index during scheduling
- Number of redundant operators
- The time to reach the balance
- The avg compaction flow during the balance
and so on.

### Teachability, Documentation, Adoption, Migration Strategy:

such as run it with the command:
```
/bench-scheduler
````