fix: support color customization per data point

Author: arjunlalb

projects/observability/src/shared/components/cartesian/cartesian-chart.component.ts

@@ -175,7 +175,10 @@ export class CartesianChartComponent<TData> implements OnChanges, OnDestroy {
         label: singleValue.context.name,
         value: defaultYDataAccessor<number | string>(singleValue.dataPoint),
         units: singleValue.context.units,
-        color: singleValue.context.color
+        color:
+          singleValue.context.getColor !== undefined
+            ? singleValue.context.getColor(singleValue.dataPoint)
+            : singleValue.context.color
       }))
     };
   }