Use an alias property for the banner icon

CURA-8564

plugins/Marketplace/resources/qml/ManagedPackages.qml

@@ -12,7 +12,7 @@ Packages
     pageTitle: catalog.i18nc("@header", "Manage packages")
 
     bannerVisible: UM.Preferences.getValue("cura/market_place_show_manage_packages_banner");
-    bannerIcon: "ArrowDoubleCircleRight"
+    bannerIcon: UM.Theme.getIcon("ArrowDoubleCircleRight")
     bannerText: catalog.i18nc("@text", "Manage your Ultimaker Cura plugins and material profiles here. Make sure to keep your plugins up to date and backup your setup regularly.")
     readMoreUrl: "" // TODO add when support page is ready
     onRemoveBanner: function() {

plugins/Marketplace/resources/qml/Materials.qml

@@ -9,7 +9,7 @@ Packages
     pageTitle: catalog.i18nc("@header", "Install Materials")
 
     bannerVisible:  UM.Preferences.getValue("cura/market_place_show_material_banner")
-    bannerIcon: "Spool"
+    bannerIcon: UM.Theme.getIcon("Spool")
     bannerText: catalog.i18nc("@text", "Streamline your workflow and customize your Ultimaker Cura experience with plugins contributed by our amazing community of users.")
     readMoreUrl: "" // TODO add when support page is ready
     onRemoveBanner: function() {

plugins/Marketplace/resources/qml/OnboardBanner.qml

@@ -11,7 +11,7 @@ import Cura 1.6 as Cura
 // Onboarding banner.
 Rectangle
 {
-    property string bannerIcon
+    property alias bannerIcon: onboardingIcon.source;
     property string bannerText
     property var onRemoveBanner
     property string readMoreUrl
@@ -28,7 +28,7 @@ Rectangle
     color: UM.Theme.getColor("action_panel_secondary")
 
     // Icon
-    Item
+    UM.RecolorImage
     {
         id: onboardingIcon
         anchors
@@ -39,12 +39,6 @@ Rectangle
         }
         width: UM.Theme.getSize("button_icon").width
         height: UM.Theme.getSize("button_icon").height
-        UM.RecolorImage
-        {
-            anchors.fill: parent
-            color: UM.Theme.getColor("primary_text")
-            source: UM.Theme.getIcon(bannerIcon)
-        }
     }
 
     // Close button

plugins/Marketplace/resources/qml/Plugins.qml

@@ -9,7 +9,7 @@ Packages
     pageTitle: catalog.i18nc("@header", "Install Plugins")
 
     bannerVisible: UM.Preferences.getValue("cura/market_place_show_plugin_banner")
-    bannerIcon: "Shop"
+    bannerIcon: UM.Theme.getIcon("Shop")
     bannerText: catalog.i18nc("@text", "Select and install material profiles optimised for your Ultimaker 3D printers.")
     readMoreUrl: "" // TODO add when support page is ready
     onRemoveBanner: function() {