Request: Average hash rate http api
XMRig/6.16.1

It would be really nice if I can check the average hash rate with the http api.
Now I have to login every single PC if I want to know. Because this average hash rate is missing from the returned summary json

```
    "hashrate": {
        "total": [3447.31, 3445.19, 4223.13],
        "highest": 15062.78
    }

```