Whether a content type is something a terminal should be asked to print.

Text, JSON, XML, and the +json/+xml suffixes every API invents — everything else is bytes, and bytes in a terminal is a beep and a broken prompt.

import { isTextual } from './http-service.ts';

isTextual('application/json; charset=utf-8'); // true
isTextual('application/vnd.api+json'); // true
isTextual('image/png'); // false
isTextual(''); // true — nothing said, so assume it can be read