Automatically load recent messages on reconnect (#3878)

* Add working reconnect recent messages

* Rename method to messagesUpdated

* Use audo declarations

* Add docs to new LimitedQueue methods

* Add more documentation, try atomic loading flag

* Update CHANGELOG.md

* Remove unused include

* Rename 'reconnected' signal to 'connected'

* Reserve before filtering on arbitrary update

* Extract recent messages fetching to own class

* Use std::atomic_flag instead of std::atomic_bool

* Add PostToThread include

* Add chatterino.recentmessages logging

* Remove unneeded parameters, lambda move capture

* Remove TwitchChannel::buildRecentMessages

* Add documentation, use more clear method name

* Reword changelog entry

I think it sounds better like this :)

* Rework how filling in missing messages is handled

This should hopefully prevent issues with filtered channels with old messages
that no longer exist in the underlying channel

* Check existing messages when looking for reply

* Clean up string distribution in file

* Try to improve documentation

* Use std::function for RecentMessagesApi

* Only trigger filledInMessages if we inserted

* Remove old unused lines

* Use make_shared<MessageLayout> instead of new MessageLayout

* Alphabetize QLogging categories

* Reorder CHANGELOG.md

src/providers/RecentMessagesApi.hpp

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "ForwardDecl.hpp"
+
+#include <QString>
+
+#include <functional>
+#include <memory>
+#include <vector>
+
+namespace chatterino {
+
+class RecentMessagesApi
+{
+public:
+    using ResultCallback = std::function<void(const std::vector<MessagePtr> &)>;
+    using ErrorCallback = std::function<void()>;
+
+    /**
+     * @brief Loads recent messages for a channel using the Recent Messages API
+     * 
+     * @param channelName Name of Twitch channel
+     * @param channelPtr Weak pointer to Channel to use to build messages
+     * @param onLoaded Callback taking the built messages as a const std::vector<MessagePtr> &
+     * @param onError Callback called when the network request fails
+     */
+    static void loadRecentMessages(const QString &channelName,
+                                   std::weak_ptr<Channel> channelPtr,
+                                   ResultCallback onLoaded,
+                                   ErrorCallback onError);
+};
+
+}  // namespace chatterino