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/settings/DevicesPage.qml

@@ -38,7 +38,7 @@ FormCard.FormCardPage {
             icon.name: "security-low"
             text: i18nc("@action:button", "Verify This Device")
             description: i18nc("@info:description", "This device is marked as insecure until it's verified by another device. It's recommended to verify as soon as possible.")
-            visible: !root.connection.isVerifiedSession()
+            visible: !root.connection.isVerifiedSession
             onClicked: {
                 root.connection.startSelfVerification();
                 const dialog = Qt.createComponent("org.kde.kirigami", "PromptDialog").createObject(QQC2.Overlay.overlay, {
@@ -94,6 +94,9 @@ FormCard.FormCardPage {
         title: i18n("Remove device")
 
         standardButtons: QQC2.Dialog.Cancel
+
+        Component.onCompleted: passwordField.forceActiveFocus()
+
         FormCard.FormCard {
             FormCard.FormTextFieldDelegate {
                 id: passwordField