Make the Notifications window non-modal

Tapping on a notification here doesn't close the window. Additionally,
you need to tap it several times for NeoChat to scroll up in a room.

Considering all of this, it would make more sense for this window to be
non-modal for now so you can have the Notifications window open while
using the main NeoChat window.

src/qml/SpaceDrawer.qml

@@ -65,7 +65,8 @@ QQC2.Control {
                     onSelected: pageStack.pushDialogLayer(Qt.createComponent('org.kde.neochat', 'NotificationsView'), {
                         connection: root.connection
                     }, {
-                        title: i18nc("@title", "Notifications")
+                        title: i18nc("@title", "Notifications"),
+                        modality: Qt.NonModal
                     })
                 }