Hide thumbnail

### Description

When using the RSS module, some RSS feed urls do not provide image thumbnails. Therefore, when I need to display RSS feed descriptions using the detailed-list style, the thumbnail placeholder still occupies space even though no image is displayed. Can a hide-thumbnail property be added to hide this placeholder? Or does this feature already exist but I haven't noticed it?

Start by locating the RSS module and the code that renders the detailed-list style, then check how thumbnail placeholders are handled when a feed has no image. Done means a configuration property can hide that placeholder without affecting feeds that provide thumbnails, with coverage for both cases.

Written by the indexing model from the issue text.