all: consider removing ExporterOption

[rakyll]

Functional options are a considered disadvantageous due their complexity, read https://middlemost.com/object-lifecycle/ for more and consider about exporting some fields on the Exporter type instead.

type Exporter struct {
     Addr string
     Insecure bool
     ServiceName string
}

func NewExporter(serviceName string) (*Exporter, error)