Provide Span.Kind for TracingInterceptor

[northpowered]

What was changed

Added span kinds for TracingInterceptor

Now, all START actions are opentelemetry.trace.SpanKind.CLIENT
and all RUN actions are opentelemetry.trace.SpanKind.SERVER

For other actions kind=INTERNAL

Why?

Before this changes all spans was INTERNAL, so it was unavailable to build service graphs for APM (ex.: Grafana Tempo)

For example, this is the service graph with INTERNAL spans:

And this is for CLIENT/SERVER:

Spans attributes now look like this:

All experiments located here
This repo is a bit raw now, and hasn`t good README, but it`ll be fixed soon

Checklist

1. Closes [Feature Request] TracingInterceptor span kinds #357

2. How was this tested:
   SDK developers reccomended testing, Integration tests were made here

3. Any docs updates needed?
   No docs updated needed

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[cretz]

Thanks for this! I did set kind properly in the .NET impl just not here for whatever reason.

I think you may need to run poe format on the repo. Left some other suggestions too.

[northpowered]

Thanks for this! I did set kind properly in the .NET impl just not here for whatever reason.

I think you may need to run poe format on the repo. Left some other suggestions too.

@cretz
Done here

• Formatted
• No default SpanKinds
• No internal kinds

[cretz]

Looks great! Will merge if/when CI passes. Thanks!