Asynchronously load affiliate links

[jimchamp]

Closes #8576

Asynchronously loads affiliate links on the book page. Now, on book page load, the prices have been replaced with the same type of loading indicator that is used for the related works carousel. This loading indicator is now a macro, but this can be reverted if another loading indicator should be used (like a skeleton loader).

As of writing, error cases are not handled gracefully (if at all). What should the behavior be if the call for partials fails? Should we retry? Should the loading indicator be replaced by some error message?

Technical

Replaced parameter page with title in the AffiliateLinks.html, as only the title was being accessed on the page object.

In order to simplify updating the view, the content of the affiliate links macro is now nested within a span. This entire span is replaced with the partially rendered HTML on fetch success.

Affiliate links in the DonateModal component are not asynchronously fetched. I'm not sure if this template is actively used today, so maybe it should be removed altogether?

Ready for review when:

• We've decided what the loading indicator should look like
• Errors are handled gracefully
• Linting errors addressed

Testing

General:

1. Visit a book page.
2. Quickly try to spot the loading indicator in the databarWork section.
3. Ensure that the loading indicator is replaced by prices.
4. Ensure that the same is true in mobile views.

Retry Flow:

1. Force the /partials handler to return an error.
2. Visit a book page.
3. Ensure that the loading indicator is replaced by a retry link.
4. Click the retry link. Ensure that only one retry link is rendered after the second failed attempt to fetch partials.
5. Revert changes to the /partials handler.
6. Click the retry link again. Ensure that the retry link is replaced by affiliate links.

Screenshot

Loading indicator in desktop view.

Loading indicator in mobile view.

Retry link in desktop view.

Retry link in mobile view.

Stakeholders