Add otel resource label and service.name handling

[ericmustin]

This PR Adds the Resource labels as span tags, and also uses the more canonical resource service.name to set the span's service when it exists.

This work brings us closer to the spec of how OTE service naming should work, and it's a pattern that's been addressed in other vendor/backend specific exporters

• https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/resource/semantic_conventions/README.md#service
• Use resource service.name as zipkin service name open-telemetry/opentelemetry-js#919
• Use resource label service.name as Jaeger service name open-telemetry/opentelemetry-java#978

Work following this will be to ensure our documentation is appropriate for onboarding as well

[ericmustin]

blocked by CI failures, checking in with opentelemetry-ruby