Streams the binary or text content of the asset identified by assetId. Returns HTTP 302 if the content is hosted at a remote URL; returns HTTP 200 with the raw content otherwise. Use the name variant (downloadPersonAssetByName) when you have the asset name but not the id. The access token is optional on this operation: omit it and Extole serves only the person's PUBLIC assets, resolving the client from the request domain. Supply a token belonging to the person to reach their PRIVATE assets. Omitting the token is the recommended way to render another person's avatar, so no token has to be embedded in an image URL.