As a user receiving image suggestions notifications, I want to quickly be able to see what image is being suggested, so that I know at first glance if it's something I want to review and easily understand the purpose of the notification.

In T292310 we are creating the UI for the image suggestions notifications, but that task does not include adding a thumbnail in the notification as seen in the design. This task is to add the thumbnail to the notification.

Acceptance Criteria

• The notification contains a small thumbnail of the media being suggested, as seen in the below design
• If the media being suggested is not an image, it should still look like a generic thumbnail (e.g. no play icon if it's a video)

Note: Per @matthiasmullie "Echo does not have support for thumbnails; IMO it’s very useful for this purpose, but we’ll also have to build such support in Echo. And we’ll have to address potential differences in width and overall style between a thumbnail and the current icons for other types of notifications."