Media Model

Create a media model for all the media message in the timeline and then setup `NeoChatMaximizeComponent` so that it can use the media model to scroll through all loaded images and video in the current room.

Depends upon libraries/kirigami-addons!105

FEATURE: 467411

src/models/mediamessagefiltermodel.h

@@ -0,0 +1,56 @@
+// SPDX-FileCopyrightText: 2023 James Graham <james.h.graham@protonmail.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+
+#pragma once
+
+#include <QSortFilterProxyModel>
+
+#include "models/collapsestateproxymodel.h"
+
+/**
+ * @class MediaMessageFilterModel
+ *
+ * This model filters a MessageEventModel for image and video messages.
+ *
+ * @sa MessageEventModel
+ */
+class MediaMessageFilterModel : public QSortFilterProxyModel
+{
+    Q_OBJECT
+public:
+    /**
+     * @brief Defines the model roles.
+     */
+    enum Roles {
+        SourceRole = CollapseStateProxyModel::LastRole + 1, /**< The mxc source URL for the item. */
+        TempSourceRole, /**< Source for the temporary content (either blurhash or mxc URL). */
+        TypeRole, /**< The type of the media (image or video). */
+        CaptionRole, /**< The caption for the item. */
+        SourceWidthRole, /**< The width of the source item. */
+        SourceHeightRole, /**< The height of the source item. */
+    };
+    Q_ENUM(Roles)
+
+    MediaMessageFilterModel(QObject *parent = nullptr);
+
+    /**
+     * @brief Custom filter to show only image and video messages.
+     */
+    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
+
+    /**
+     * @brief Get the given role value at the given index.
+     *
+     * @sa QSortFilterProxyModel::data
+     */
+    [[nodiscard]] QVariant data(const QModelIndex &idx, int role = Qt::DisplayRole) const override;
+
+    /**
+     * @brief Returns a mapping from Role enum values to role names.
+     *
+     * @sa Roles, QAbstractProxyModel::roleNames()
+     */
+    [[nodiscard]] QHash<int, QByteArray> roleNames() const override;
+
+    Q_INVOKABLE int getRowForSourceItem(int sourceRow) const;
+};