Align trace ID and span ID naming with other SDKs

[piotrooo]

What is the expected behavior?
The opentelemetry-php/contrib-auto-psr3 project sets traceId and spanId in camelCase:

https://github.com/opentelemetry-php/contrib-auto-psr3/blob/eebb2559a84e9fd653cbf736c2209f44772c8cc2/src/Psr3Instrumentation.php#L57-L58

What is the actual behavior?
All other SDKs use trace_id and span_id written in snake_case.
Is this intentional, or should it be changed to comply with other SDKs?

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[brettmc]

I think it's ok to change to snake case, if you want to create a PR for it

[bobstrecansky]

@piotrooo are you planning on doing this work, or should we label it help wanted?

[piotrooo]

@piotrooo are you planning on doing this work, or should we label it help wanted?

@bobstrecansky yes, you should label it as help wanted.