Ability to add more comments with the Commenter Feature

[debuggerpk]

GCP CloudSQL Commenter add a couple of keys e.g. action, route etc which are visible in CloudSQL Query insights. In those keys, action key is very interesting. It would be wonderful if we can add more comments to the query.

I have been playing the library a little bit but I can't seem to wrap to head around this line. https://github.com/XSAM/otelsql/blob/dc433894c80088b924034a7d0a79cac7e4863b31/commenter.go#L61

My debugging investigation shows that traceparent becomes available in context after this line. I believe this happens because we are instantiating it with propagation.NewCompositeTextMapPropagator()

Is there a way we can set more keys for commentCarrier when setting the context of the query?

PS: thankyou for the wonderful work.