[Glitch] Add customizable thumbnails for audio and video attachments

Port 64aac30733 to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/features/status/components/detailed_status.js

@@ -142,7 +142,8 @@ export default class DetailedStatus extends ImmutablePureComponent {
             src={attachment.get('url')}
             alt={attachment.get('description')}
             duration={attachment.getIn(['meta', 'original', 'duration'], 0)}
-            poster={status.getIn(['account', 'avatar_static'])}
+            poster={attachment.get('preview_url') || status.getIn(['account', 'avatar_static'])}
+            blurhash={attachment.get('blurhash')}
             height={150}
           />
         );