Closes #9545

Follow up after #9556, which adds the necessary logic to load the moderation queue in paginated chunks, starting with the first page, and loading extra pages as you scroll.

The amount of annotations we load per page is 20. That should ensure there's a scrollable area in most screen resolutions, but this will be even more so after proper annotation cards have been implemented.

Considerations

The logic to decide whether or not more pages should be loaded is based on the one we implemented in LMS for the dashboard filter dropdowns, with the difference that here it works based on the window scroll, rather a specific DOM element's.

On top of that, the logic is build for scroll-based pagination, but supporting page-number-based pagination should not be too hard. We would just have to change the loadNextPage function to allow passing the page number to load, and stop tracking the value internally.

Testing steps

1. Create a bunch of annotations in a group. At least more than 5 for testing purposes.
2. Apply this diff, so that annotations are loaded in small-enough chunks and you don't need to create a lot of annotations just to testing this:

   diff --git a/h/static/scripts/group-forms/utils/api/fetch-group-annotations.ts b/h/static/scripts/group-forms/utils/api/fetch-group-annotations.ts
   index 5a43bc8d0..f1a111c05 100644
   --- a/h/static/scripts/group-forms/utils/api/fetch-group-annotations.ts
   +++ b/h/static/scripts/group-forms/utils/api/fetch-group-annotations.ts
   @@ -20,7 +20,7 @@ export async function fetchGroupAnnotations(
   ): Promise<FetchGroupAnnotationsResult> {
     const query: Record<string, string | number> = paginationToParams({
       pageNumber,
   -    pageSize: 20,
   +    pageSize: 5,
     });
     if (moderationStatus) {
       query.moderation_status = moderationStatus;

3. Go to http://localhost:5000/users/devdata_admin, and on the "Groups" dropdown, select the group in which you created annotations.
4. Go to the "Moderation" tab.
5. Resize the browser window so that you need to scroll to see all existing annotations.
6. Scroll down, and observe how the next chunk of annotations is loaded.
7. Continue scrolling until all annotations have been loaded, and notice it stops loading annotations.
8. Change the filtering moderation status, and notice how the list is reset to start loading annotations from scratch.