[configgrpc] respect auth extension error codes

[therealpandey]

Component(s)

otelcol

Is your feature request related to a problem? Please describe.

The configgrpc helper ignores the error returned by a custom authenticator and always returns a status.Error(codes.Unauthenticated, err.Error()).

https://github.com/open-telemetry/opentelemetry-collector/blame/6cd9c4e26feb910f19720950c8337af28194a70d/config/configgrpc/configgrpc.go#L614

Describe the solution you'd like

If the authenticator extensions sends an error of type "google.golang.org/grpc/status".Error, it should be respected and propagated to the upstream client.

Use cases:

1. The authenticator extension might itself want to send retryable errors.

Describe alternatives you've considered

Additional context

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[therealpandey]

Happy to work on a PR to get this out

[dmathieu]

IMHO a PR for this would make sense.

[therealpandey]

@dmathieu

I can do a simple assertion of the error type with an if-else loop. However, that might not be backwards compatible.

Would you be okay with that?

[dmathieu]

configgrpc is not a stable package, so that's fine.

[therealpandey]

Raised PR here @dmathieu
#14010