Support for native histograms

[jml]

Native histograms (aka sparse histograms, aka high-res histograms) are on their way to being production ready. It would be wonderful if the Node prom-client supported them.

From the (Prometheus docs](https://prometheus.io/docs/concepts/metric_types/#histogram):

A native histogram requires only one time series, which includes a dynamic number of buckets in addition to the sum and count of observations. Native histograms allow much higher resolution at a fraction of the cost.

They aren't quite a stable feature yet, but I figure it would be useful to me & others to have an issue to gather together any discussion on implementing them for this client.

Some relevant links:

• Prometheus milestone for full native histogram support
• PromCon 2022 talk introducing native histograms
• Go client implementation of histograms, including support for native histograms