Show image overlay for direct links to media images

[towerofnix]

This is an idea from Tangle in November: #hsmusic-chat

i just realized we should make it so when you click a link (in commentary) to an image thats saved on the wiki, it should display in the image overlay

As they note, kind of like the Unofficial Homestuck Collection.

We only connected this with commentary at the time, but it's probably also appropriate for additional file lists. The browser-provided "save link as..." / "download linked file" context menu option would still work, of course, same as cover artworks. (Lan, #hsmusic-chat)

Maybe a pictograph for an image would also be appropriate: they are links for going somewhere to view a thing (not to take an action on the page - #211), but they show that differently than normally following a link (sort of like external links - #449).

On the technical end, linkAlbumAdditionalFile - used by additional files - and linkPathFromMedia - used by transformContent - are currently unrelated components. If we want the new behavior in both contexts, we should make a code connection here. The image overlay generally shows thumbnails, so we need to provide the same relevant information as the image component does.