Library name

Azure.Messaging.ServiceBus, Azure.Messaging.EventHubs

Please describe the feature.

Related to #37698
ServiceBus aspire component depends on SB SDK to emit metrics.

Implementation ideas:

• we don't need metrics abstractions in Core and can use metrics API from DiagnosticSource 6.0.0 directly
• we should keep them behind experimental flag for the time being (OTel conventions are still experimental)

Context:

• Messaging metrics semantics are being defined in OpenTelemetry
• Java SB and EH SDKs emit metrics (and will conform to otel ones once the PR above is merged):