instrument/http: add span.kind & component tags to WrapHandlerFunc

[darccio]

What does this PR do?

Adds missing tags span.kind and component for net/http autoinstrumentation using instrument.WrapHandlerFunc.

The root cause is that it uses httptrace.TraceAndServe under the hood, that assumes these tags are added by the caller (like httptrace.WrapHandler).

Reviewer's Checklist

• Changed code has unit tests for its functionality.

[ahmed-mez]

Any reason why we shouldn't have this logic in dd-trace-go?

[darccio]

@ahmed-mez I thought of that, but it seems that httptrace.TraceAndServe can be used directly and indirectly through httptrace.WrapHandler, that sets these tags before calling httptrace.TraceAndServe. This is why I chose to do it in Orchestrion instead.

I agree this should be in dd-trace-go but it could break expectations of current users. Maybe it's a good candidate to be included in our v2.