Prometheus exporter export instrumentation scope attributes

[pellared]

Make Prometheus exporter to export instrumentation scope attributes

Blocked by:

• https://github.com/open-telemetry/opentelemetry-go/issues/3368

Prometheus exporter is REQUIRED to set the instrumentation scope attributes on the otel_scope_info metric: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk_exporters/prometheus.md and https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/compatibility/prometheus_and_openmetrics.md#instrumentation-scope-1:

Scope attributes MUST also be added as labels following the rules described in the Metric Attributes section below.

However, most likely it is better to mark it as blocked by:

• https://github.com/open-telemetry/opentelemetry-specification/issues/4223

CC @dashpole