Case-insensitive visibility checking for printers

In Qt's ListModel, the section headers collect items case-insensitively. However, when checking whether a printer should be visible (when the section header is expanded) was still checked case-sensitively. As a result, it was hiding all printers that did not use the same casing in its manufacturer name, e.g. FlashForge vs. Flashforge.

Fixes #11125.

resources/qml/WelcomePages/AddLocalPrinterScrollView.qml

@@ -186,7 +186,7 @@ Item
 
                     checked: ListView.view.currentIndex == index
                     text: name
-                    visible: base.currentSection == section
+                    visible: base.currentSection.toLowerCase() === section.toLowerCase()
                     onClicked: ListView.view.currentIndex = index
                 }
             }