hash_util: Set channel URL based on user setting.

We now render channel feed URL or channel topics list URL in
all elements based on user setting.

web/shared/src/internal_url.js.flow

@@ -28,3 +28,8 @@ declare export function by_stream_topic_url(
     topic: string,
     maybe_get_stream_name: (id: number) => ?string,
 ): string;
+
+declare export function by_channel_topic_list_url(
+    stream_id: number,
+    maybe_get_stream_name: (id: number) => ?string,
+): string;