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.cpp

@@ -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
+
+#include "threepidmodel.h"
+
+#include "neochatconnection.h"
+
+ThreePIdModel::ThreePIdModel(NeoChatConnection *connection)
+    : QAbstractListModel(connection)
+{
+    Q_ASSERT(connection);
+    connect(connection, &NeoChatConnection::stateChanged, this, [this]() {
+        const auto connection = dynamic_cast<NeoChatConnection *>(this->parent());
+        if (connection != nullptr && connection->isLoggedIn()) {
+            const auto threePIdJob = connection->callApi<Quotient::GetAccount3PIDsJob>();
+            connect(threePIdJob, &Quotient::BaseJob::success, this, [this, threePIdJob]() {
+                beginResetModel();
+                m_threePIds = threePIdJob->threepids();
+                endResetModel();
+            });
+        }
+    });
+}
+
+QVariant ThreePIdModel::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid()) {
+        return {};
+    }
+    if (index.row() >= rowCount()) {
+        qDebug() << "ThreePIdModel, something's wrong: index.row() >= m_threePIds.count()";
+        return {};
+    }
+
+    if (role == AddressRole) {
+        return m_threePIds.at(index.row()).address;
+    }
+    if (role == MediumRole) {
+        return m_threePIds.at(index.row()).medium;
+    }
+
+    return {};
+}
+
+int ThreePIdModel::rowCount(const QModelIndex &parent) const
+{
+    Q_UNUSED(parent)
+    return m_threePIds.count();
+}
+
+QHash<int, QByteArray> ThreePIdModel::roleNames() const
+{
+    return {
+        {AddressRole, QByteArrayLiteral("address")},
+        {MediumRole, QByteArrayLiteral("medium")},
+    };
+}