Move remaining code to app module

There's still some stuff that could potentially go elsewhere but I think it's enough for now.

src/app/identityserverhelper.h

@@ -0,0 +1,88 @@
+// 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 <QObject>
+#include <QQmlEngine>
+
+#include <Quotient/jobs/basejob.h>
+
+class NeoChatConnection;
+
+/**
+ * @class IdentityServerHelper
+ *
+ * This class is designed to help the process of setting an identity server for the account.
+ * It will manage the various stages of verification and authentication.
+ */
+class IdentityServerHelper : public QObject
+{
+    Q_OBJECT
+    QML_ELEMENT
+
+    /**
+     * @brief The connection to add a 3PID to.
+     */
+    Q_PROPERTY(NeoChatConnection *connection READ connection WRITE setConnection NOTIFY connectionChanged)
+
+    /**
+     * @brief The URL for the desired server.
+     */
+    Q_PROPERTY(QString url READ url WRITE setUrl NOTIFY urlChanged)
+
+    /**
+     * @brief The current status.
+     */
+    Q_PROPERTY(IdServerStatus status READ status NOTIFY statusChanged)
+
+public:
+    /**
+     * @brief The current status for adding an identity server
+     */
+    enum IdServerStatus {
+        Ready, /**< The process is ready to start. I.e. there is no ongoing attempt to set a new server. */
+        Valid, /**< The server URL is valid. */
+        Invalid, /**< The server URL is invalid. */
+        Match, /**< The server URL is the one that is already configured. */
+        Other, /**< An unknown problem occurred. */
+    };
+    Q_ENUM(IdServerStatus)
+
+    explicit IdentityServerHelper(QObject *parent = nullptr);
+
+    [[nodiscard]] NeoChatConnection *connection() const;
+    void setConnection(NeoChatConnection *connection);
+
+    [[nodiscard]] QString url() const;
+    void setUrl(const QString &url);
+
+    [[nodiscard]] IdServerStatus status() const;
+
+    /**
+     * @brief Set the current URL as the user's identity server.
+     *
+     * Will do nothing if the URL isn't a valid identity server.
+     */
+    Q_INVOKABLE void setIdentityServer();
+
+    /**
+     * @brief Clear the user's identity server.
+     */
+    Q_INVOKABLE void clearIdentityServer();
+
+Q_SIGNALS:
+    void connectionChanged();
+    void urlChanged();
+    void statusChanged();
+
+private:
+    QPointer<NeoChatConnection> m_connection;
+
+    IdServerStatus m_status = Ready;
+    QString m_url;
+
+    QPointer<QNetworkReply> m_idServerCheckRequest;
+
+    void checkUrl();
+};