Support for a histogram buckets api

[ewoolsey]

Feature Request

Motivation

One thing my team is looking for is the ability to specify histogram buckets when registering a histogram. This can currently be done at the meter provider level, but there are a few reasons why this would be useful at the actual metric call site. One reason being ease of configuration. A library should be able to suggest an appropriate bucket distribution that a consumer can then accept by default or override.

Proposal

I haven't fully evaluated how this could work yet, but I think It should be possible with using the view method for otel meters. Not sure exactly what the api should look like, perhaps:

info!(histogram.my_hist = my_var, buckets = ExpBuckets { .. });