Commit export template changes

Publishes all pending changes of an export template as a new revision. **Authorization.** The same rule as `POST /V2/export-templates/{id}/publish`: admin and internal users can commit any export template, external users only the ones they own. Internal viewers can't commit.

curl -X POST "https://export-template-api.productsup.com/V1/export-templates/string/commit"

{
  "data": {
    "revisionId": "01977d42-b51d-70b4-afed-b5522b5ce896"
  }
}

{
  "errors": {
    "message": "Resource access denied."
  }
}