feat: Support SortMergeJoin proto serde (#17296)

* Implement ser/de part of SortMergeJoin

* add round trip tests for sort merge join

* add filter test to roundtrip

Author: milenkovicm

datafusion/proto/proto/datafusion.proto

@@ -729,6 +729,7 @@ message PhysicalPlanNode {
     JsonScanExecNode json_scan = 31;
     CooperativeExecNode cooperative = 32;
     GenerateSeriesNode generate_series = 33;
+    SortMergeJoinExecNode sort_merge_join = 34;
   }
 }
 
@@ -1343,3 +1344,13 @@ message GenerateSeriesNode {
         GenerateSeriesArgsDate date_args = 6;
     }
 }
+
+message SortMergeJoinExecNode {
+  PhysicalPlanNode left = 1;
+  PhysicalPlanNode right = 2;
+  repeated JoinOn on = 3;
+  datafusion_common.JoinType join_type = 4;
+  JoinFilter filter = 5;
+  repeated SortExprNode sort_options = 6;
+  datafusion_common.NullEquality null_equality = 7;
+}