Prometheus exporter export instrumentation scope attributes

[pellared]

Make Prometheus exporter to export instrumentation scope attributes

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.

We need to also solve this for Go:

• [Prometheus and OpenMetrics] Handle scheme URL and scope attributes as identifying opentelemetry-specification#4223

CC @dashpole

[pellared]

PoC: #5947