otelkit: Refactor option type

[pellared]

Why

Per #851

What

Adhere to https://github.com/open-telemetry/opentelemetry-go/blob/main/CONTRIBUTING.md#configuration

[codecov]

Codecov Report

Merging #858 (75cebb3) into main (01fdab7) will increase coverage by 0.7%.
The diff coverage is 85.6%.

@@           Coverage Diff           @@
##            main    #858     +/-   ##
=======================================
+ Coverage   78.4%   79.1%   +0.7%     
=======================================
  Files         62      62             
  Lines       2737    2744      +7     
=======================================
+ Hits        2146    2172     +26     
+ Misses       456     440     -16     
+ Partials     135     132      -3     

Impacted Files	Coverage Δ
detectors/gcp/gce.go	7.3% <0.0%> (ø)
detectors/gcp/gke.go	0.0% <0.0%> (ø)
exporters/metric/dogstatsd/internal/statsd/conn.go	59.2% <ø> (ø)
...github.com/aws/aws-sdk-go-v2/otelaws/attributes.go	100.0% <ø> (ø)
...ion/github.com/aws/aws-sdk-go-v2/otelaws/config.go	100.0% <ø> (ø)
...umentation/net/http/httptrace/otelhttptrace/api.go	100.0% <ø> (ø)
...on/net/http/httptrace/otelhttptrace/clienttrace.go	76.2% <ø> (ø)
instrumentation/net/http/otelhttp/labeler.go	84.6% <ø> (ø)
detectors/aws/eks/detector.go	32.7% <33.3%> (+3.6%)	⬆️
instrumentation/net/http/otelhttp/config.go	78.0% <77.7%> (ø)
... and 28 more