Add medium quality "Folder" icon

CURA-8202

plugins/PrepareStage/PrepareMenu.qml

@@ -97,7 +97,7 @@ Item
                 {
                     id: buttonIcon
                     anchors.centerIn: parent
-                    source: UM.Theme.getIcon("Folder")
+                    source: UM.Theme.getIcon("Folder", "medium")
                     width: UM.Theme.getSize("button_icon").width
                     height: UM.Theme.getSize("button_icon").height
                     color: UM.Theme.getColor("icon")

resources/themes/cura-light/icons/medium/Folder.svg

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!-- Generator: Adobe Illustrator 24.3.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 viewBox="0 0 30 30" style="enable-background:new 0 0 30 30;" xml:space="preserve">
+<g id="Layer_1">
+	<path d="M24,9c0-1.65-1.35-3-3-3h-9l-1-1H6C4.34,5,3,6.34,3,8v14c0,1.66,1.34,3,3,3h18c1.66,0,3-1.34,3-3V12C27,10.34,25.66,9,24,9
+		z M25,23H5V7h5.17l4,4H25V23z"/>
+</g>
+<g id="Comments">
+</g>
+</svg>