Add fetch_continuation_token back (required by #2215)

src/invidious/yt_backend/extractors_utils.cr

@@ -0,0 +1,17 @@
+def fetch_continuation_token(items : Array(JSON::Any))
+  # Fetches the continuation token from an array of items
+  return items.last["continuationItemRenderer"]?
+    .try &.["continuationEndpoint"]["continuationCommand"]["token"].as_s
+end
+
+def fetch_continuation_token(initial_data : Hash(String, JSON::Any))
+  # Fetches the continuation token from initial data
+  if initial_data["onResponseReceivedActions"]?
+    continuation_items = initial_data["onResponseReceivedActions"][0]["appendContinuationItemsAction"]["continuationItems"]
+  else
+    tab = extract_selected_tab(initial_data["contents"]["twoColumnBrowseResultsRenderer"]["tabs"])
+    continuation_items = tab["content"]["sectionListRenderer"]["contents"][0]["itemSectionRenderer"]["contents"][0]["gridRenderer"]["items"]
+  end
+
+  return fetch_continuation_token(continuation_items.as_a)
+end