Allow Prometheus exporter to add resource attributes to metric attributes

**Describe the solution you'd like**
Implement it per the spec: https://github.com/open-telemetry/opentelemetry-specification/pull/3761
Described here: https://github.com/open-telemetry/opentelemetry-specification/issues/3705

