Bufgix/producing traceparent propagation

[toizo]

The way how Traceparent header was built had an issue such that the started activity/span id was not included. This PR fixed that, among others:

• activity names include message type names (this way, it is possible to group activities uniquely per message type)
• OpenTelemetry.Api nuget version upgraded to v1.8
• kafka-specific activity tags were encapsulated into its own class
• Messaging attributes are updated to reflect the current spec:
  • messaging.destination_kind was dropped
  • messaging.destination was changed to messaging.destination.name

[toizo]

Initially, there was an issue with some serialization tests. This is because some tests use a static invocation of ActivitySource.AddActivityListener(...) that affects whether traceparent and baggage message headers included in the envelope.

I did not find any good way of isolating that static class, so I decided to make the serialization tests part of a same test collection - this prevents them running in parallel.