Set explicitely parent in MaximizeComponent

Currently it uses applicationWindow().overlay which works but is
not ideal for multiple reasons:

- This as a tendency to breaks unexpectedly
- It can't be optimized by the qml compiler

So we are trying to move away from these construct everywhere.

src/qml/GroupChatDrawerHeader.qml

@@ -89,7 +89,7 @@ ColumnLayout {
             }
 
             onClicked: {
-                let map = Qt.createComponent('org.kde.neochat', 'QrCodeMaximizeComponent').createObject(parent, {
+                let map = Qt.createComponent('org.kde.neochat', 'QrCodeMaximizeComponent').createObject(QQC2.Overlay.overlay, {
                     text: barcode.content,
                     title: root.room ? root.room.displayName : "",
                     subtitle: root.room ? root.room.id : "",

src/qml/RoomPage.qml

@@ -309,6 +309,7 @@ Kirigami.Page {
         NeochatMaximizeComponent {
             currentRoom: root.currentRoom
             model: root.mediaMessageFilterModel
+            parent: root.QQC2.Overlay.overlay
         }
     }
 }

src/qml/UserDetailDialog.qml

@@ -84,7 +84,7 @@ Kirigami.Dialog {
                 }
 
                 onClicked: {
-                    let map = qrMaximizeComponent.createObject(parent, {
+                    let map = Qt.createComponent('org.kde.neochat', 'QrCodeMaximizeComponent').createObject(QQC2.Overlay.overlay, {
                         text: barcode.content,
                         title: root.room ? root.room.member(root.user.id).displayName : root.user.displayName,
                         subtitle: root.user.id,
@@ -265,8 +265,4 @@ Kirigami.Dialog {
             }
         }
     }
-    Component {
-        id: qrMaximizeComponent
-        QrCodeMaximizeComponent {}
-    }
 }