Use the forget function to leave a room everywhere

Use the forget function to leave a room everywhere this is both for consistency and to reduce dependencies. This way no dependency on RoomManager is required to leave a room and since in all cases they have an object they can just call the function.

src/libneochat/neochatconnection.h

@@ -150,6 +150,14 @@ public:
      */
     Q_INVOKABLE void createSpace(const QString &name, const QString &topic, const QString &parent = {}, bool setChildParent = false);
 
+    /**
+     * @brief Send /forget to the server and delete room locally.
+     *
+     * @note This wraps around the Quotient::Connection::forgetRoom() to allow
+     *       roomAboutToBeLeft() to be emitted.
+     */
+    Quotient::ForgetRoomJob *forgetRoom(const QString &id);
+
     /**
      * @brief Whether a direct chat with the user exists.
      */
@@ -224,6 +232,11 @@ Q_SIGNALS:
      */
     void errorOccured(const QString &error);
 
+    /**
+     * @brief The given room ID is about to be forgotten.
+     */
+    void roomAboutToBeLeft(const QString &id);
+
 private:
     static bool m_globalUrlPreviewDefault;
     static PushRuleAction::Action m_defaultAction;