Split message content into its own module

This is laying some groundwork for the rich text chatbar.

src/messagecontent/models/itinerarymodel.h

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: 2024 Tobias Fella <tobias.fella@kde.org>
+// SPDX-License-Identifier: LGPL-2.0-or-later
+
+#pragma once
+
+#include <QAbstractListModel>
+#include <QJsonArray>
+#include <QPointer>
+#include <QQmlEngine>
+#include <QString>
+
+class ItineraryModel : public QAbstractListModel
+{
+    Q_OBJECT
+    QML_ELEMENT
+    QML_UNCREATABLE("")
+
+public:
+    enum Roles {
+        NameRole = Qt::DisplayRole,
+        TypeRole,
+        DepartureLocationRole,
+        ArrivalLocationRole,
+        DepartureTimeRole,
+        DepartureAddressRole,
+        ArrivalTimeRole,
+        ArrivalAddressRole,
+        AddressRole,
+        StartTimeRole,
+        EndTimeRole,
+        DeparturePlatformRole,
+        ArrivalPlatformRole,
+        CoachRole,
+        SeatRole,
+    };
+    Q_ENUM(Roles)
+    explicit ItineraryModel(QObject *parent = nullptr);
+
+    QVariant data(const QModelIndex &index, int role) const override;
+    int rowCount(const QModelIndex &parent = {}) const override;
+
+    QHash<int, QByteArray> roleNames() const override;
+
+    QString path() const;
+    void setPath(const QString &path);
+
+    Q_INVOKABLE void sendToItinerary();
+
+Q_SIGNALS:
+    void loaded();
+    void loadErrorOccurred();
+
+private:
+    QJsonArray m_data;
+    QString m_path;
+    void loadData();
+};