Add optional WithAttributes to support bound instruments

[dashpole]

Fixes #4126

For open-telemetry/opentelemetry-go#7743.

Changes

Allow binding attributes to an instrument prior to measurement calls. This is useful for performance and ergonomics of the metrics API. For Go, it allows users to do:

counter.WithAttributes(attribute.String("foo", "bar")).Add(ctx, 1)

Instead of (very poor performance):

counter.Add(ctx, 1, WithAttributes(attribute.String("foo", "bar")))

Or, instead of the ugly, performant version.

I'm working on a prototype in Go.

• Related issues #
• Related OTEP(s) #
• Links to the prototypes (when adding or changing features)
• CHANGELOG.md file updated for non-trivial changes
  • For trivial changes, include [chore] in the PR title to skip the changelog check
• Spec compliance matrix updated if necessary

[dashpole]

I'm still in discussions with the other Go maintainers about whether we would implement this API if it was added to the spec. I'm planning to leave this as a draft until that point. If other language SIGs are interested in pushing this forward, feel free to write prototypes, and I'll mark it as ready for review after that point.

One thing that came up during discussion is that this differs from how attributes are provided for logs and spans. It is an open question whether this pattern would make sense for logs or spans. I haven't had time to investigate this yet.