Use imagecache for all AssetImageProvider images

TextureImageCacheCollector is added to the existing async image cache
to generate thumbnails for image files.

Fixes: QDS-8581
Change-Id: I4a334b3241688d7a61a0560463bff32763a216a5
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

share/qtcreator/qmldesigner/materialBrowserQmlSource/TextureItem.qml

@@ -61,9 +61,10 @@ Rectangle {
     Image {
         source: "image://materialBrowserTex/" + textureSource
         asynchronous: true
-        sourceSize.width: root.width - 10
-        sourceSize.height: root.height - 10
+        width: root.width - 10
+        height: root.height - 10
         anchors.centerIn: parent
         smooth: true
+        fillMode: Image.PreserveAspectFit
     }
 }

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/UrlChooser.qml

@@ -116,8 +116,6 @@ Row {
                     Image {
                         id: thumbnail
                         asynchronous: true
-                        sourceSize.height: 96
-                        sourceSize.width: 96
                         height: 96
                         width: 96
                         fillMode: Image.PreserveAspectFit

share/qtcreator/qmldesigner/textureEditorQmlSource/TextureEditorTopSection.qml

@@ -35,8 +35,9 @@ Column {
         Image {
             id: texturePreview
             asynchronous: true
-            sourceSize.width: 150
-            sourceSize.height: 150
+            width: 150
+            height: 150
+            fillMode: Image.PreserveAspectFit
             anchors.centerIn: parent
             source: "image://qmldesigner_thumbnails/" + resolveResourcePath(backendValues.source.valueToString)
         }