message_list_data_cache: Update when receiving new messages.

If we receive a message that we can add to the data cache without
talking to the server, we do that, otherwise we remove it from the
cache to avoid us having wrong filter status cached.

web/src/message_list_data_cache.ts

@@ -88,3 +88,12 @@ export function get_superset_datasets(filter: Filter): MessageListData[] {
 
     return [...superset_datasets, all_messages_data.all_messages_data];
 }
+
+export function remove(filter: Filter): void {
+    for (const [key, cached_data] of cache.entries()) {
+        if (cached_data.filter.equals(filter)) {
+            cache.delete(key);
+            return;
+        }
+    }
+}