Show the desktop shell in Chinese under zh_CN

shell/Ui/SearchableDropdown.qml

@@ -21,8 +21,8 @@ Item {
   property string label: ""
   property string value: ""
   property var options: []
-  property string placeholderText: "Search..."
-  property string emptyText: "No matches"
+  property string placeholderText: I18n.tr("Search...")
+  property string emptyText: I18n.tr("No matches")
   property string triggerLabel: ""
 
   property color foreground: Color.popups.text