[AURON #1889] Implement monotonically_increasing_id() function

[ShreyeshArangath]

Which issue does this PR close?

Closes #1889

Rationale for this change

Adds's support for non-deterministic function, as part of #1833

What changes are included in this PR?

Implements native support for Spark's `monotonically_increasing_id()`` function in Auron.

Functionality TL;DR:
The monotonically_increasing_id() function generates unique, monotonically increasing 64-bit integers across all partitions. Each partition generates IDs using the formula:

id := (partition_id << 33) | row_number

• Each ID is globally unique across all partitions
• IDs increase monotonically within each partition
• The upper 31 bits encode the partition ID, while the lower 33 bits encode the row number within that partition

Are there any user-facing changes?

N/A

How was this patch tested?

Unit tests

[Copilot]

Pull request overview

Implements native support for Spark’s monotonically_increasing_id() as a non-deterministic physical expression in Auron, wiring it through the Spark shims, protobuf plan representation, and the Rust planner and execution engine.

Changes:

• Adds a MonotonicallyIncreasingIdExprNode to the protobuf PhysicalExprNode oneof and wires it through the Scala ShimsImpl.convertMoreExprWithFallback.
• Introduces SparkMonotonicallyIncreasingIdExpr in datafusion-ext-exprs, including unit tests that validate type, nullability, monotonicity, partition offsets, and partition separation.
• Extends the Rust PhysicalPlanner to build SparkMonotonicallyIncreasingIdExpr from the new protobuf expression type and exposes the module from datafusion-ext-exprs.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
spark-extension-shims-spark/src/main/scala/org/apache/spark/sql/auron/ShimsImpl.scala	Maps Spark’s MonotonicallyIncreasingID Catalyst expression to the new protobuf MonotonicIncreasingIdExprNode for native planning.
native-engine/datafusion-ext-exprs/src/spark_monotonically_increasing_id.rs	Implements the physical expression that generates 64-bit partition-scoped monotonically increasing IDs and adds unit tests for behavior.
native-engine/datafusion-ext-exprs/src/lib.rs	Exposes the new spark_monotonically_increasing_id module from the extension expressions crate.
native-engine/auron-planner/src/planner.rs	Deserializes the new protobuf MonotonicIncreasingIdExpr into SparkMonotonicallyIncreasingIdExpr during physical planning.
native-engine/auron-planner/proto/auron.proto	Extends the physical expression protobuf with MonotonicIncreasingIdExprNode and its field in PhysicalExprNode, and relocates SparkPartitionIdExprNode to avoid duplication.

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[ShreyeshArangath]

@cxzl25 can I get a re-review on this? Thanks!