Improve first-run UX

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

imports/NeoChat/Component/Login/LoginRegister.qml

@@ -0,0 +1,35 @@
+/**
+ * SPDX-FileCopyrightText: 2020 Tobias Fella <fella@posteo.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+import QtQuick 2.14
+import QtQuick.Controls 2.14 as Controls
+import QtQuick.Layouts 1.14
+
+import org.kde.kirigami 2.12 as Kirigami
+
+import org.kde.neochat 1.0
+
+import NeoChat.Component.Login 1.0
+
+LoginStep {
+    id: loginRegister
+
+    Layout.alignment: Qt.AlignHCenter
+
+    Controls.Button {
+        Layout.alignment: Qt.AlignHCenter
+        text: i18n("Login")
+        Layout.preferredWidth: Kirigami.Units.gridUnit * 12
+        onClicked: processed("qrc:/imports/NeoChat/Component/Login/Login.qml")
+    }
+
+    Controls.Button {
+        Layout.alignment: Qt.AlignHCenter
+        text: i18n("Register")
+        Layout.preferredWidth: Kirigami.Units.gridUnit * 12
+        onClicked: processed("qrc:/imports/NeoChat/Component/Login/Homeserver.qml")
+    }
+}