QmlDesigner: Clear components view search box upon load

i.e. upon changing from edit mode to QDS mode. This also removed a
warning.

Change-Id: Ibd3ee3bd30febfcee9a05cb87047e79b8ed1bf61
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

share/qtcreator/qmldesigner/itemLibraryQmlSources/Assets.qml

@@ -48,7 +48,7 @@ Item {
 
     function clearSearchFilter()
     {
-        searchBox.text = "";
+        searchBox.clear();
     }
 
     function updateDropExtFiles(drag)

share/qtcreator/qmldesigner/itemLibraryQmlSources/ItemsView.qml

@@ -91,6 +91,12 @@ Item {
         itemContextMenu.close()
     }
 
+    // Called from C++
+    function clearSearchFilter()
+    {
+        searchBox.clear();
+    }
+
     // Called also from C++
     function switchToComponentsView()
     {

share/qtcreator/qmldesigner/materialBrowserQmlSource/MaterialBrowser.qml

@@ -56,7 +56,7 @@ Item {
     // Called from C++
     function clearSearchFilter()
     {
-        searchBox.clearSearchFilter();
+        searchBox.clear();
     }
 
     MouseArea {

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

@@ -33,7 +33,7 @@ Item {
 
     property alias text: searchFilterText.text
 
-    function clearSearchFilter()
+    function clear()
     {
         searchFilterText.text = "";
     }