Improve first-run UX

- Replace LoginPage with step-by-step approach to support different login flows
- Implement login using SSO

src/login.h

@@ -0,0 +1,85 @@
+/**
+ * SPDX-FileCopyrightText: 2020 Tobias Fella <fella@posteo.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#pragma once
+
+#include <QObject>
+
+#include "csapi/wellknown.h"
+#include "connection.h"
+
+using namespace Quotient;
+
+class Login : public QObject
+{
+    Q_OBJECT
+
+    Q_PROPERTY(bool homeserverReachable READ homeserverReachable NOTIFY homeserverReachableChanged)
+    Q_PROPERTY(bool testing READ testing NOTIFY testingChanged)
+    Q_PROPERTY(QString matrixId READ matrixId WRITE setMatrixId NOTIFY matrixIdChanged)
+    Q_PROPERTY(QString password READ password WRITE setPassword NOTIFY passwordChanged)
+    Q_PROPERTY(QString deviceName READ deviceName WRITE setDeviceName NOTIFY deviceNameChanged)
+    Q_PROPERTY(bool supportsSso READ supportsSso NOTIFY loginFlowsChanged STORED false)
+    Q_PROPERTY(bool supportsPassword READ supportsPassword NOTIFY loginFlowsChanged STORED false)
+    Q_PROPERTY(QUrl ssoUrl READ ssoUrl NOTIFY ssoUrlChanged)
+    Q_PROPERTY(bool isLoggingIn READ isLoggingIn NOTIFY isLoggingInChanged)
+
+public:
+    explicit Login(QObject *parent = nullptr);
+
+    Q_INVOKABLE void init();
+
+    bool homeserverReachable() const;
+
+    QString matrixId() const;
+    void setMatrixId(const QString &matrixId);
+
+    QString password() const;
+    void setPassword(const QString &password);
+
+    QString deviceName() const;
+    void setDeviceName(const QString &deviceName);
+
+    bool supportsPassword() const;
+    bool supportsSso() const;
+
+    bool testing() const;
+
+    QUrl ssoUrl() const;
+
+    bool isLoggingIn() const;
+
+    Q_INVOKABLE void login();
+    Q_INVOKABLE void loginWithSso();
+
+Q_SIGNALS:
+    void homeserverReachableChanged();
+    void testHomeserverFinished();
+    void matrixIdChanged();
+    void passwordChanged();
+    void deviceNameChanged();
+    void initialSyncFinished();
+    void loginFlowsChanged();
+    void ssoUrlChanged();
+    void connected();
+    void errorOccured(QString message);
+    void testingChanged();
+    void isLoggingInChanged();
+
+private:
+    void setHomeserverReachable(bool reachable);
+
+    bool m_homeserverReachable;
+    QString m_matrixId;
+    QString m_password;
+    QString m_deviceName;
+    bool m_supportsSso = false;
+    bool m_supportsPassword = false;
+    Connection *m_connection = nullptr;
+    QUrl m_ssoUrl;
+    bool m_testing;
+    bool m_isLoggingIn = false;
+};