Add visualisation of the account's third party IDs in the account editor.

A category won't be shown if there are no relevant IDs (will add the ability to add new ones later).

Part of network/neochat#565

![image](/uploads/7da00b0b4acf90d145c09969ac2a91e1/image.png)

src/models/threepidmodel.h

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: 2024 James Graham <james.h.graham@protonmail.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+
+#pragma once
+
+#include <QAbstractListModel>
+#include <QQmlEngine>
+
+#include <Quotient/csapi/administrative_contact.h>
+
+class NeoChatConnection;
+
+/**
+ * @class ThreePIdModel
+ *
+ * This class defines the model for visualising an account's 3PIDs.
+ */
+class ThreePIdModel : public QAbstractListModel
+{
+    Q_OBJECT
+    QML_ELEMENT
+
+public:
+    /**
+     * @brief Defines the model roles.
+     */
+    enum EventRoles {
+        AddressRole = Qt::DisplayRole, /**< The third-party identifier address. */
+        MediumRole, /**< The medium of the third-party identifier. One of: [email, msisdn]. */
+    };
+
+    explicit ThreePIdModel(NeoChatConnection *parent);
+
+    /**
+     * @brief Get the given role value at the given index.
+     *
+     * @sa QAbstractItemModel::data
+     */
+    [[nodiscard]] QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+
+    /**
+     * @brief Number of rows in the model.
+     *
+     * @sa QAbstractItemModel::rowCount
+     */
+    [[nodiscard]] int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+
+    /**
+     * @brief Returns a mapping from Role enum values to role names.
+     *
+     * @sa EventRoles, QAbstractItemModel::roleNames()
+     */
+    [[nodiscard]] QHash<int, QByteArray> roleNames() const override;
+
+private:
+    QVector<Quotient::GetAccount3PIDsJob::ThirdPartyIdentifier> m_threePIds;
+};