Render labels using Text.QtRendering on OSX

Fonts were looking a bit to thick on when using `Text.NativeRendering`, so using `Text.QtRendering` instead. After this the font weight looks identical to figma (as far as I can see).

In this commit I also changed all `Label`'s to `UM.Label`'s and removed default properties where I could.

CURA-9154

resources/qml/WelcomePages/ImageTile.qml

@@ -4,7 +4,7 @@
 import QtQuick 2.10
 import QtQuick.Controls 2.3
 
-import UM 1.3 as UM
+import UM 1.5 as UM
 
 
 //
@@ -18,7 +18,7 @@ Column
     property alias text: label.text
     property alias imageSource: image.source
 
-    Label
+    UM.Label
     {
         id: label
         width: image.width
@@ -26,9 +26,6 @@ Column
         horizontalAlignment: Text.AlignHCenter
         text: ""
         wrapMode: Text.WordWrap
-        font: UM.Theme.getFont("default")
-        color: UM.Theme.getColor("text")
-        renderType: Text.NativeRendering
     }
 
     Image