Add grip lines to bottom of resizable panel

Looks all right now.

Contributes to issue CURA-6054.

resources/qml/PrintSetupSelector/PrintSetupSelectorContents.qml

@@ -176,6 +176,24 @@ Item
                     UM.Preferences.setValue("view/settings_list_height", h);
                 }
             }
+
+            UM.RecolorImage
+            {
+                width: parent.width * 0.05
+                sourceSize.height: height
+                sourceSize.width: width
+                anchors
+                {
+                    horizontalCenter: parent.horizontalCenter
+                    top: parent.top
+                    topMargin: UM.Theme.getSize("thick_lining").height
+                    bottom: parent.bottom
+                    bottomMargin: UM.Theme.getSize("thick_lining").height
+                }
+
+                source: UM.Theme.getIcon("grip_lines")
+                color: UM.Theme.getColor("lining")
+            }
         }
     }
 }

resources/themes/cura-light/icons/grip_lines.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 30 6">
+    <rect width="30" height="2" rx="1" ry="1" />
+    <rect width="30" height="2" rx="1" ry="1" y="4" />
+</svg>