src/vs/platform/environment/node/argvHelper.ts/addArg
export function addArg(argv: string[], ...args: string[]): string[] {
	const endOfArgsMarkerIndex = argv.indexOf('--');
	if (endOfArgsMarkerIndex === -1) {
		argv.push(...args);
	} else {
		// if the we have an argument "--" (end of argument marker)
		// we cannot add arguments at the end. rather, we add
		// arguments before the "--" marker.
		argv.splice(endOfArgsMarkerIndex, 0, ...args);
	}

	return argv;
}