AG-17505 Unwrap only a grouping value in a pending range bound

A grouping value is the one bound shape carrying its value in a nested field,
so keying the unwrap on `value` alone would also strip a serialisable date or
bigint down to its raw payload.

Author: lsjroberts

packages/ag-charts-community/src/chart/update/dataWindowProcessor.ts

@@ -20,7 +20,7 @@ const DEFAULT_ZOOM: ZoomMinMax = { min: 0, max: 1 };
 type WindowBound = AgDataSourceCallbackParams['windowStart'];
 
 function windowBound(value: unknown): WindowBound {
-    if (isObject(value) && 'value' in value) return windowBound(value.value);
+    if (isObject(value) && 'groupPercentage' in value) return windowBound(value.value);
     if (isString(value) || isFiniteNumber(value) || isValidDate(value)) return value;
 }