Implement request for user data erasure

This adds UI for MSC4025 to the account deactivation dialog, if the
server supports it. We also switch away from our
customDeactivateAccountJob to libQuotient's.

Fixes #670.

src/qml/ConfirmDeactivateAccountDialog.qml

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 import QtQuick
+import QtQuick.Layouts
 import QtQuick.Controls as QQC2
 
 import org.kde.kirigamiaddons.formcard as FormCard
@@ -18,12 +19,21 @@ Kirigami.PromptDialog {
 
     dialogType: Kirigami.PromptDialog.Warning
 
-    mainItem: FormCard.FormTextFieldDelegate {
-        id: passwordField
-        label: i18nc("@label:textbox", "Password")
-        echoMode: TextInput.Password
-        horizontalPadding: 0
-        bottomPadding: 0
+    mainItem: ColumnLayout {
+        FormCard.FormTextFieldDelegate {
+            id: passwordField
+            label: i18nc("@label:textbox", "Password")
+            echoMode: TextInput.Password
+            horizontalPadding: 0
+            bottomPadding: 0
+        }
+
+        FormCard.FormCheckDelegate {
+            id: eraseDelegate
+            text: i18nc("@label:checkbox", "Erase Data")
+            description: i18nc("@info", "Request your server to delete as much user data as possible.")
+            visible: connection.canEraseData
+        }
     }
 
     footer: QQC2.DialogButtonBox {
@@ -34,7 +44,7 @@ Kirigami.PromptDialog {
             icon.name: "emblem-warning"
             enabled: passwordField.text.length > 0
             onClicked: {
-                root.connection.deactivateAccount(passwordField.text);
+                root.connection.deactivateAccount(passwordField.text, eraseDelegate.checked);
                 root.closeDialog();
             }
         }