QmlDesigner: Notify save indicator on row/column deletion

Task-number: QDS-12499
Change-Id: I8d61bc3abdd9b8bda299a93c88579f2d0e392221
Reviewed-by: Ali Kianian <ali.kianian@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Patch Build Bot <ci_patchbuild_bot@qt.io>
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

src/plugins/qmldesigner/components/collectioneditor/collectiondetailsmodel.cpp

@@ -153,6 +153,7 @@ bool CollectionDetailsModel::removeColumns(int column, int count, const QModelIn
         removeRows(0, rowCount(parent), parent);
 
     ensureSingleCell();
+    setHasUnsavedChanges(true);
     return columnsRemoved;
 }
 
@@ -169,6 +170,7 @@ bool CollectionDetailsModel::removeRows(int row, int count, const QModelIndex &p
     endRemoveRows();
 
     ensureSingleCell();
+    setHasUnsavedChanges(true);
     return rowsRemoved;
 }