Don't add group chats that we are not a member of

Td also fetches updates from groups that we are not a member of
like those appear linked_chat_id.
Checking if we are a member of those groups first helps to prevent
those linked chats to pop up.

Read td's docs here for more info:
https://core.telegram.org/tdlib/docs/classtd_1_1td__api_1_1supergroup_full_info.html#aff3925ba397314a7645686c223495d09

Signed-off-by: Björn Bidar <bjorn.bidar@thaodan.de>

td-client.cpp

@@ -89,7 +89,18 @@ void PurpleTdClient::processUpdate(td::td_api::Object &update)
     case td::td_api::updateNewChat::ID: {
         auto &newChat = static_cast<td::td_api::updateNewChat &>(update);
         purple_debug_misc(config::pluginId, "Incoming update: new chat\n");
-        addChat(std::move(newChat.chat_));
+        if (newChat.chat_->type_->get_id() == td::td_api::chatTypePrivate::ID ||
+            newChat.chat_->type_->get_id() == td::td_api::chatTypeSecret::ID  ||
+            m_data.isGroupChatWithMembership(*newChat.chat_.get()))
+            addChat(std::move(newChat.chat_));
+        else {
+            purple_debug_misc(config::pluginId,
+                              "Incoming update: ignorig ID=%d\n",
+                              update.get_id());
+            purple_debug_misc(config::pluginId,
+                              "Not adding a group that we are not a member of");
+        }
+
         break;
     }