Allow parent/child relationship in Opentelemetry spans

[meum]

Proposed Changes

Adds an option to set remote span as parent rather than link when propagating Opentelemetry context between the publisher and receiver.
See issue #1666

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Further Comments

[lmolkova]

LGTM from otel semconv perspective!

[meum]

Does it make more sense to remove the TracingLinkType enum, and just have a bool UsePublisherAsParent?
My original reason for making an enum was that we might want something more advanced in the future, e.g. making it configurable per message, or automatically determining if parent/child makes sense based on the exchange type. But I'm not sure what that would look like.

[stebet]

LGTM :)