Change animation on feed generation screen in web UI (#33311)

app/javascript/mastodon/components/regeneration_indicator.tsx

@@ -0,0 +1,26 @@
+import { FormattedMessage } from 'react-intl';
+
+import { GIF } from './gif';
+
+export const RegenerationIndicator: React.FC = () => (
+  <div className='regeneration-indicator'>
+    <GIF
+      src='/loading.gif'
+      staticSrc='/loading.png'
+      className='regeneration-indicator__figure'
+    />
+
+    <div className='regeneration-indicator__label'>
+      <strong>
+        <FormattedMessage
+          id='regeneration_indicator.preparing_your_home_feed'
+          defaultMessage='Preparing your home feed…'
+        />
+      </strong>
+      <FormattedMessage
+        id='regeneration_indicator.please_stand_by'
+        defaultMessage='Please stand by.'
+      />
+    </div>
+  </div>
+);