Review public API for `carbonexporter`

[mx-psi]

See base issue for details. Assigning to @pjanotti

[github-actions]

This issue has been inactive for 60 days. It will be closed in 60 days if there is no activity. To ping code owners by adding a component label, see Adding Labels via Comments, or if you are unsure of which component this issue relates to, please ping @open-telemetry/collector-contrib-triagers. If this issue is still relevant, please ping the code owners or leave a comment explaining why it is still relevant. Otherwise, please close it.

Pinging code owners:

• exporter/carbon: @pjanotti

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[mx-psi]

Closing as wontfix, see #4055 (comment)