Improve images resizing quality accross the board

- Using mipmap: true and smooth: true for images that are downscaled
(avatar, icons, ...)
- Using mipmap: false and smooth: true for images that are potentially
upscaled (background, overview, ...)

Bar/Modules/CustomTrayMenu.qml

@@ -115,6 +115,8 @@ PopupWindow {
                     Image {
                         Layout.preferredWidth: 16
                         Layout.preferredHeight: 16
+                        smooth: true
+                        mipmap: true
                         source: modelData?.icon ?? ""
                         visible: (modelData?.icon ?? "") !== ""
                         fillMode: Image.PreserveAspectFit