feat: Add Live Emote Updates for BTTV (#4147)

This feature is enabled by default and can be disabled in settings with the "Enable BTTV live emotes updates" setting.

Co-authored-by: Felanbird <41973452+Felanbird@users.noreply.github.com>
Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/providers/bttv/BttvLiveUpdates.hpp

@@ -0,0 +1,57 @@
+#pragma once
+
+#include "providers/bttv/liveupdates/BttvLiveUpdateMessages.hpp"
+#include "providers/bttv/liveupdates/BttvLiveUpdateSubscription.hpp"
+#include "providers/liveupdates/BasicPubSubManager.hpp"
+#include "util/QStringHash.hpp"
+
+#include <pajlada/signals/signal.hpp>
+
+#include <unordered_set>
+
+namespace chatterino {
+
+class BttvLiveUpdates : public BasicPubSubManager<BttvLiveUpdateSubscription>
+{
+    template <typename T>
+    using Signal =
+        pajlada::Signals::Signal<T>;  // type-id is vector<T, Alloc<T>>
+
+public:
+    BttvLiveUpdates(QString host);
+
+    struct {
+        Signal<BttvLiveUpdateEmoteUpdateAddMessage> emoteAdded;
+        Signal<BttvLiveUpdateEmoteUpdateAddMessage> emoteUpdated;
+        Signal<BttvLiveUpdateEmoteRemoveMessage> emoteRemoved;
+    } signals_;  // NOLINT(readability-identifier-naming)
+
+    /**
+     * Joins a Twitch channel by its id (without any prefix like 'twitch:')
+     * if it's not already joined.
+     *
+     * @param channelID the Twitch channel-id of the broadcaster.
+     * @param userName the Twitch username of the current user.
+     */
+    void joinChannel(const QString &channelID, const QString &userName);
+
+    /**
+     * Parts a twitch channel by its id (without any prefix like 'twitch:')
+     * if it's joined.
+     *
+     * @param id the Twitch channel-id of the broadcaster.
+     */
+    void partChannel(const QString &id);
+
+protected:
+    void onMessage(
+        websocketpp::connection_hdl hdl,
+        BasicPubSubManager<BttvLiveUpdateSubscription>::WebsocketMessagePtr msg)
+        override;
+
+private:
+    // Contains all joined Twitch channel-ids
+    std::unordered_set<QString> joinedChannels_;
+};
+
+}  // namespace chatterino