[Feature] Metrics SDK: allow metric readers to filter Meters during Collect()

[marcalff]

When metrics are exported to different endpoints by different exporters, it is necessary to express somehow which metric goes to which exporter.

Currently this is not possible, because a metric reader exports all the meters and metrics defined on a meter provider.

This is a new feature to improve usefulness and expressiveness of which data is exported, and where to.

Desired filtering is on a meter by meter basis, for efficiency at runtime, and ease of configuration.

This feature depends on the following spec change:

• Metrics SDK: allow metric readers to filter Meters during Collect() opentelemetry-specification#3617

[github-actions]

This issue was marked as stale due to lack of activity.