Reads qunitx run's argv into a target and its settings.

import * as Script from './run.ts';
import * as Failure from '../result/failure.ts';

// Defined, not invoked: reads package.json off the real filesystem.
async function configure() {
  const invocation = await Script.setup(['seed.ts', '--browser=firefox']).result();
  return Failure.is(invocation) ? null : invocation.settings.browser; // 'firefox'
}