Use separate context menu size for menus

Instead of re-using the setting controls. It's not a setting.

Contributes to issue CURA-8688.

resources/qml/Widgets/Menu.qml

@@ -14,12 +14,12 @@ UM.Menu
     id: menu
     padding: 0
 
-    implicitWidth: UM.Theme.getSize("setting_control").width
+    width: UM.Theme.getSize("context_menu").width
 
     delegate: Cura.MenuItem {}
     background: Rectangle
     {
-        color: UM.Theme.getColor("setting_control")
-        border.color: UM.Theme.getColor("setting_control_border")
+        color: UM.Theme.getColor("main_background")
+        border.color: UM.Theme.getColor("lining")
     }
 }

resources/qml/Widgets/MenuItem.qml

@@ -13,7 +13,7 @@ UM.MenuItem
 {
     id: menuItem
 
-    implicitHeight: UM.Theme.getSize("setting_control").height + UM.Theme.getSize("narrow_margin").height
+    height: UM.Theme.getSize("context_menu").height
     opacity: enabled ? 1.0 : 0.5
 
     arrow: UM.RecolorImage

resources/themes/cura-light/theme.json

@@ -573,6 +573,8 @@
         "medium_button": [2.5, 2.5],
         "medium_button_icon": [2, 2],
 
+        "context_menu": [20, 2],
+
         "favorites_row": [2, 2],
         "favorites_button": [2, 2],
         "favorites_button_icon": [1.2, 1.2],