RecordBatch to Prometheus JSON format conversion

[waynexia]

What problem does the new feature solve?

The preliminary requirement of #1016.

What does the feature do?

Support to convert our query result (in RecordBatch) into Prometheus' result format, which looks like

[
  {
    "metric": { "<label_name>": "<label_value>", ... },
    "value": [ <unix_time>, "<sample_value>" ],
    "histogram": [ <unix_time>, <histogram> ]
  },
  ...
]

and

[
  {
    "metric": { "<label_name>": "<label_value>", ... },
    "values": [ [ <unix_time>, "<sample_value>" ], ... ],
    "histograms": [ [ <unix_time>, <histogram> ], ... ]
  },
  ...
]

Implementation challenges

No response