Add support for SSO authentication

src/gui/Pages/AddAccount/SignInSso.qml

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+import QtQuick 2.12
+import QtQuick.Layouts 1.12
+import "../../Base"
+import "../../Base/Buttons"
+
+SignInBase {
+    id: page
+
+    function takeFocus() { urlField.forceActiveFocus() }
+
+    function startSignIn() {
+        errorMessage.text = ""
+
+        page.loginFuture = py.callCoro("start_sso_auth", [serverUrl], url => {
+            urlField.text           = url
+            urlField.cursorPosition = 0
+
+            Qt.openUrlExternally(url)
+
+            page.loginFuture = py.callCoro("continue_sso_auth", [], userId => {
+                page.loginFuture = null
+                page.finishSignIn(userId)
+            })
+        })
+    }
+
+
+    applyButton.text: qsTr("Waiting")
+    applyButton.loading: true
+    Component.onCompleted: page.startSignIn()
+
+    HLabel {
+        wrapMode: HLabel.Wrap
+        text: qsTr(
+            "Complete the single sign-on process in your web browser to " +
+            "continue.\n\n" +
+            "If no page appeared, you can also manually open this address:"
+        )
+
+        Layout.fillWidth: true
+    }
+
+    HTextArea {
+        id: urlField
+        width: parent.width
+        readOnly: true
+        radius: 0
+        wrapMode: HTextArea.WrapAnywhere
+
+        Layout.fillWidth: true
+        Layout.fillHeight: true
+    }
+}