getParams from parrot-core should be exposed

[smackfu]

Given a somewhat complex matcher like this:

  const getBook = ({ url }, match) => {
    const path = '/books/:bookId';
    if (match({ path, method: 'GET' })) {
      const { bookId } = getParams(url, path);
      const book = books.find((book) => book.bookId === bookId);
      if (!book) {
        return { status: 404 };
      }
      return { status: 200, body: book };
    }
    return null;
  };

The getParams function that is needed is not exposed by parrot, even though it has an implementation.

It would be convenient if that was available for consumers to use.