updateArgv rendered as one line, for printing.

The half a person reads: it goes in a refusal, and in the header an upgrade prints before it runs the thing. It exists so no caller formats that line itself — one rendering, so every message shows the same command, and the day one of these needs quoting there is one place to add it.

import * as Channel from './channel.ts';

Channel.updateCommand({ kind: 'npm-global', prefix: '/usr/lib' }, '1.0.0'); // 'npm install -g qunitx-cli@1.0.0'
Channel.updateCommand({ kind: 'deno-cache', entry: '/c/deno/npm/x' }, '1.0.0'); // 'deno run -A npm:qunitx-cli@1.0.0'