function argStringToArray(argString) {
    const args = [];
    let inQuotes = false;
    let escaped = false;
    let arg = '';
    function append(c) {
        // we only escape double quotes.
        if (escaped && c !== '"') {
            arg += '\\';
        }
        arg += c;
        escaped = false;
    }
    for (let i = 0; i < argString.length; i++) {
        const c = argString.charAt(i);
        if (c === '"') {
            if (!escaped) {
                inQuotes = !inQuotes;
            }
            else {
                append(c);
            }
            continue;
        }
        if (c === '\\' && escaped) {
            append(c);
            continue;
        }
        if (c === '\\' && inQuotes) {
            escaped = true;
            continue;
        }
        if (c === ' ' && !inQuotes) {
            if (arg.length > 0) {
                args.push(arg);
                arg = '';
            }
            continue;
        }
        append(c);
    }
    if (arg.length > 0) {
        args.push(arg.trim());
    }
    return args;
}
Convert an arg string to an array of args. Handles escaping

@param    argString   string of arguments
@returns  string[]    array of arguments