add interval splitting for bar charts

pdb-js/src/app/visualization-page/visualization-page.component.ts

@@ -50,6 +50,9 @@ export class VisualizationPageComponent implements OnInit {
   enableGallery = false;
   splitBy = null;
   y2AxisAvailable = false;
+  
+  intervalUnit = 'NO_INTERVAL';
+  intervalValue = 1;
 
   constructor(private plotService: PlotService, private snackBar: MatSnackBar) {
   }
@@ -163,6 +166,8 @@ export class VisualizationPageComponent implements OnInit {
     request.aggregates = aggregates; 
     request.keyOutside = false;
     request.generateThumbnail = this.enableGallery;
+    request.intervalUnit = this.intervalUnit;
+    request.intervalValue = this.intervalValue;
     return request;
   }