function prefixPath({ url, siteUrl, pathPrefix = `` }) {
  return new URL(pathPrefix + url, siteUrl).toString()
}
@name prefixPath

Properly handles prefixing relative path with site domain, Gatsby pathPrefix and AssetPrefix

@param {string} url - string containing relative path
@param {string} siteUrl - results of the resolveSiteUrl function
@returns {string}