[JS][js/plugins/google-genai] when enabling debug traces the debug span must represent the uderlying REST API call

[pavelgj]

the sendMessage should have inputs of the REST call, and raw outputs of the REST call. In this example above, the REST API succeeded, so it should be shown as green, but the error in the converters happened on the Genkit side, so the error is in the model, not the REST call.