[AURON #2152] Implement native function of map_from_arrays

[weimingdiit]

Which issue does this PR close?

Closes #2152

Rationale for this change

This PR adds native support for Spark map_from_arrays(keys, values) through Auron’s extension-function path.

Spark defines this function as creating a map from the given key/value arrays, with the requirement that all elements in keys must be non-null. This change implements that behavior in Auron and adds regression coverage.

map_from_arrays(...) was not supported in Auron’s native execution path.

This PR extends native map-function coverage while keeping behavior aligned with Spark semantics, following the existing extension-function pattern already used for Spark-specific functions such as map_concat(...).

What changes are included in this PR?

This PR:

• adds MapFromArrays conversion in NativeConverters
• registers Spark_MapFromArrays in datafusion-ext-functions
• implements map_from_arrays(...) in spark_map.rs
• enforces Spark-compatible null-key rejection
• handles row-level null propagation
• adds Scala and Rust regression tests

Are there any user-facing changes?

Yes.
Queries using map_from_arrays(keys, values) can now run through Auron’s native extension-function path.

How was this patch tested?

UT.

[Copilot]

Pull request overview

Adds native execution support for Spark’s map_from_arrays(keys, values) via Auron’s extension-function path, aligning behavior with Spark semantics (null propagation + null-key rejection) and adding regression coverage.

Changes:

• Adds Spark plan conversion for MapFromArrays to the native extension-function call (Spark_MapFromArrays).
• Registers and implements the Spark_MapFromArrays extension function in the native engine (Arrow/DataFusion).
• Adds Scala + Rust tests covering baseline behavior and null-key rejection.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
spark-extension/src/main/scala/org/apache/spark/sql/auron/NativeConverters.scala	Converts Spark MapFromArrays expression into the Spark_MapFromArrays native extension function call.
spark-extension-shims-spark/src/test/scala/org/apache/auron/AuronFunctionSuite.scala	Adds Spark-side regression tests for map_from_arrays, including a null-key rejection case.
native-engine/datafusion-ext-functions/src/spark_map.rs	Implements map_from_arrays in Rust, including Spark-like null propagation and null-key/duplicate-key errors, plus Rust unit tests.
native-engine/datafusion-ext-functions/src/lib.rs	Registers Spark_MapFromArrays for extension-function dispatch.

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[weimingdiit]

@slfan1989 Thanks for your review and merge!