Issue #3490047 by andileco, nikathone: Provide a way to identify chart...

Issue #3490047 by andileco, nikathone: Provide a way to identify chart attachment added to chart render array

src/Plugin/views/style/ChartsPluginStyleChart.php

@@ -519,6 +519,7 @@ class ChartsPluginStyleChart extends StylePluginBase implements ContainerFactory
             $subchart[$key]['#data'] = $processed_data;
           }
           $chart[$key] = $subchart[$key];
+          $chart[$key]['#chart_attachment_id'] = $child_display_handler->display['id'];
           // If the subchart is a different type than the parent chart, set
           // the #chart_type property on the individual chart data elements.
           if ($subchart['#chart_type'] !== $chart['#chart_type']) {