OTLP exporter settings

[jskiba]

Is your feature request related to a problem? Please describe.
I was playing with the tutorial (it didn't work out btw but maybe it's my fault) and then I wanted to test it with an external OTel ingestion endpoint and visualizers but I ran into an obstacle because my OTel ingestion requires an access token to ingest any telemetry. I haven't found any spans exporter related settings available. It would be convenient to send traces directly from go-instrumentation binary instead of setting up an OTel contrib collector that acts as a proxy to my external service.

Describe the solution you'd like
Can there be some additional settings for the exporter like here https://github.com/open-telemetry/opentelemetry-collector/tree/main/exporter/otlpexporter ?

Describe alternatives you've considered
Maybe it could be set the same way it is done in otlpexporter? I mean via a file?