feat: Add support for Spark Pi math expression

spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala

@@ -106,6 +106,7 @@ object QueryPlanSerde extends Logging with CometExprShim {
     classOf[Log2] -> CometLog2,
     classOf[Log10] -> CometLog10,
     classOf[Multiply] -> CometMultiply,
+    classOf[Pi] -> CometScalarFunction("pi"),
     classOf[Pow] -> CometScalarFunction("pow"),
     classOf[Rand] -> CometRand,
     classOf[Randn] -> CometRandn,

spark/src/test/resources/sql-tests/expressions/math/pi.sql

@@ -0,0 +1,31 @@
+-- Licensed to the Apache Software Foundation (ASF) under one
+-- or more contributor license agreements.  See the NOTICE file
+-- distributed with this work for additional information
+-- regarding copyright ownership.  The ASF licenses this file
+-- to you under the Apache License, Version 2.0 (the
+-- "License"); you may not use this file except in compliance
+-- with the License.  You may obtain a copy of the License at
+--
+--   http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing,
+-- software distributed under the License is distributed on an
+-- "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+-- KIND, either express or implied.  See the License for the
+-- specific language governing permissions and limitations
+-- under the License.
+
+-- ConfigMatrix: parquet.enable.dictionary=false,true
+
+statement
+CREATE TABLE test_pi(d double) USING parquet
+
+statement
+INSERT INTO test_pi VALUES (1.0)
+
+query tolerance=1e-15
+SELECT pi() FROM test_pi
+
+-- literal arguments
+query tolerance=1e-15
+SELECT pi()