[SPARK-31187][SQL] Sort the whole-stage codegen debug output by codegenStageId

### What changes were proposed in this pull request?

Spark SQL's whole-stage codegen (WSCG) supports dumping the generated code to help with debugging. One way to get the generated code is through `df.queryExecution.debug.codegen`, or SQL `EXPLAIN CODEGEN` statement.

The generated code is currently printed without specific ordering, which can make debugging a bit annoying. This PR makes a minor improvement to sort the codegen dump by the `codegenStageId`, ascending.

After this change, the following query:
```scala
spark.range(10).agg(sum('id)).queryExecution.debug.codegen
```
will always dump the generated code in a natural, stable order. A version of this example with shorter output is:
```
spark.range(10).agg(sum('id)).queryExecution.debug.codegenToSeq.map(_._1).foreach(println)
*(1) HashAggregate(keys=[], functions=[partial_sum(id#8L)], output=[sum#15L])
+- *(1) Range (0, 10, step=1, splits=16)

*(2) HashAggregate(keys=[], functions=[sum(id#8L)], output=[sum(id)#12L])
+- Exchange SinglePartition, true, [id=#30]
   +- *(1) HashAggregate(keys=[], functions=[partial_sum(id#8L)], output=[sum#15L])
      +- *(1) Range (0, 10, step=1, splits=16)
```

The number of codegen stages within a single SQL query tends to be very small, most likely < 50, so the overhead of adding the sorting shouldn't be significant.

### Why are the changes needed?

Minor improvement to aid WSCG debugging.

### Does this PR introduce any user-facing change?

No user-facing change for end-users; minor change for developers who debug WSCG generated code.

### How was this patch tested?

Manually tested the output; all other tests still pass.

Closes #27955 from rednaxelafx/codegen.

Authored-by: Kris Mok <[email protected]>
Signed-off-by: Takeshi Yamamuro <[email protected]>
(cherry picked from commit a177628)
Signed-off-by: Takeshi Yamamuro <[email protected]>

Author: rednaxelafx

sql/core/src/main/scala/org/apache/spark/sql/execution/debug/package.scala

@@ -113,7 +113,7 @@ package object debug {
         s
       case s => s
     }
-    codegenSubtrees.toSeq.map { subtree =>
+    codegenSubtrees.toSeq.sortBy(_.codegenStageId).map { subtree =>
       val (_, source) = subtree.doCodeGen()
       val codeStats = try {
         CodeGenerator.compile(source)._2