[NSE-794] Fix count() with decimal value

native-sql-engine/core/src/main/scala/com/intel/oap/execution/ColumnarHashAggregateExec.scala

@@ -272,6 +272,10 @@ case class ColumnarHashAggregateExec(
               case t: BooleanType =>
                 vectors(idx)
                   .put(0, res.asInstanceOf[Boolean].booleanValue())
+              case t: DecimalType =>
+                // count() does not care the real value
+                vectors(idx)
+                  .put(0, res.asInstanceOf[Number].intValue())
               case other =>
                 throw new UnsupportedOperationException(s"$other is not supported.")
             }