[Glitch] Display fallback link card thumbnail when none is given

Port 1512af2811cb5b2ffccac5452eb291b1af46f89d to glitch-soc

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

@@ -195,6 +195,12 @@ export default class Card extends React.PureComponent {
           {thumbnail}
         </div>
       );
+    } else {
+      embed = (
+        <div className='status-card__image'>
+          <i className='fa fa-file-text' />
+        </div>
+      );
     }
 
     return (

app/javascript/flavours/glitch/styles/components/status.scss

@@ -740,6 +740,15 @@ a.status-card {
   flex: 0 0 100px;
   background: lighten($ui-base-color, 8%);
   position: relative;
+
+  .fa {
+    font-size: 21px;
+    position: absolute;
+    transform-origin: 50% 50%;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+  }
 }
 
 .status-card.horizontal {