Add in-app notifications for moderation actions/warnings (#30065)

app/javascript/styles/mastodon/components.scss

@@ -2180,7 +2180,8 @@ a.account__display-name {
   }
 }
 
-.notification__relationships-severance-event {
+.notification__relationships-severance-event,
+.notification__moderation-warning {
   display: flex;
   gap: 16px;
   color: $secondary-text-color;