Downloads are not properly loaded on TopicsPage and TopicsContentPage

[rtibbles]

Observed behavior

We currently load the first page of download requests

There's no guarantee (if someone has a lot of download requests) that the currently displayed resource(s) will be included in those first 100

Expected behavior

For the TopicsPage - download filtered by the displayed resource ids.
Also, when doing any 'load more' behaviour, ensure that additional download requests are loaded for the newly fetched resources.

For the TopicsContentPage - download filtered by the displayed resource id.

In both cases, we should show a loading state in place of the add/remove download button until the data has been loaded.