fix missing api in spark40 shim

Signed-off-by: Yuan <[email protected]>

Author: zhouyuan

shims/spark40/src/main/scala/org/apache/gluten/sql/shims/spark40/Spark40Shims.scala

@@ -700,6 +700,22 @@ class Spark40Shims extends SparkShims {
     plan.offset
   }
 
+  override def extractExpressionTimestampAddUnit(exp: Expression): Option[Seq[String]] = {
+    exp match {
+      case timestampAdd: TimestampAdd =>
+        Option.apply(Seq(timestampAdd.unit, timestampAdd.timeZoneId.getOrElse("")))
+      case _ => Option.empty
+    }
+  }
+
+  override def extractExpressionTimestampDiffUnit(exp: Expression): Option[String] = {
+    exp match {
+      case timestampDiff: TimestampDiff =>
+        Some(timestampDiff.unit)
+      case _ => Option.empty
+    }
+  }
+
   override def widerDecimalType(d1: DecimalType, d2: DecimalType): DecimalType = {
     DecimalPrecisionTypeCoercion.widerDecimalType(d1, d2)
   }