Turn NeoChatConnection::isVerifiedSession into a notifiable property

This should allow the devices page to hide the "Verify this Device"
warning, once you actually complete verification. I also made sure to
update the other consumer - the menu item under the user menu.

Additionally, I also fixed the password field not being automatically
focused when trying to remove a device.

src/app/qml/AccountMenu.qml

@@ -88,7 +88,7 @@ KirigamiComponents.ConvergentContextMenu {
     Kirigami.Action {
         text: i18nc("@action:inmenu", "Verify This Device")
         icon.name: "security-low"
-        visible: !root.connection.isVerifiedSession()
+        visible: !root.connection.isVerifiedSession
         onTriggered: {
             root.connection.startSelfVerification();
             const dialog = Qt.createComponent("org.kde.kirigami", "PromptDialog").createObject(QQC2.Overlay.overlay, {

src/app/qml/KeyVerificationDialog.qml

@@ -4,6 +4,7 @@
 import QtQuick
 import QtQuick.Controls as QQC2
 import QtQuick.Layouts
+import QtQuick.Window
 import QtQml
 
 import org.kde.kirigami as Kirigami
@@ -170,6 +171,7 @@ Kirigami.Page {
                     return "";
                 }
             }
+            onDone: root.QQC2.Window.window.close()
         }
     }