feat(meta): add get back pressure RPC for UI dashboard

[yufansong]

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What's changed and what's your intention?

In #13830, we want to embedded a back pressure rate metrics for dashbaord UI. In this PR, I add a API to get the back pressure from all compute node to meta node.

But I still need to implement the calculation steps. The way to calculate the rate:

1. Get the (previous) back pressure metrics 1 in time 1.
2. Get the (current) back pressure metrics 2 in time 2. Do (metrics 2 - metrics 1)/(time2 - time1).
3. Then make the current back pressure as the previous metrics and repeat step 1 and step 2 every 15 seconds.

In meta node, I didn't find a good way to do this crobjob, also not find a good place to storage the previous metrics in memory. May try to implement the logic in ui frontend or some place in meta in following PR.

Result:
If you deploy and request the http://127.0.0.1:5691/api/metrics/back_pressures, will get result:

{
    "backPressureInfos": [
        {
            "actorId": "8",
            "fragmentId": "2",
            "downstreamFragmentId": "1",
            "value": 483665.0
        },
        {
            "actorId": "15",
            "fragmentId": "4",
            "downstreamFragmentId": "3",
            "value": 239666.0
        },
        {
            "actorId": "7",
            "fragmentId": "2",
            "downstreamFragmentId": "1",
            "value": 317250.0
        },
        .....
    ]
}

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[fuyufjh]

The rest LGTM

[fuyufjh]

The data types can be integers.

We use string in Prometheus because Prometheus require all labels to be string. But sicne this interface is particularly designed for back-pressire (as it's named BackPressureInfo), it's not that case.

[yezizp2012]

Sorry for my late response.

[yezizp2012]

We can list all streaming worker nodes directly here by metadata manager, then we can call the RPC here and avoid to add interface for worker manager and controller.

[yezizp2012]

We can perform RPC calls concurrently.

[BugenZhao]

I believe it's better to put it in MonitorService.