[tracing/azotel] Enable span link and propagation support

[karenychen]

• The purpose of this PR is explained in this or a referenced issue.
• The PR does not update generated files.
  • These files are managed by the codegen framework at Azure/autorest.go.
• Tests are included and/or updated for code changes.
• Updates to module CHANGELOG.md are included.
• MIT license headers are included in each file.

Description

Support span link and context propagation in tracing/azotel.

The PR adds OTel implementation to:

• Provider.NewPropagator() to return a propagation.TraceContext() propagator for context propagation.
• tracing.LinkFromContext() to return a OTel Span Link with the passed in attributes attached to it.
• Span.AddLink() to add an Otel Span Link to the current span.
• Span.SpanContext() to return the OTel Span Context of the current span.

There is no public facing API change in this PR.

[github-actions]

Thank you for your contribution @karenychen! We will review the pull request and get back to you soon.

[jhendrixMSFT]

Will also need a changelog entry.