[AURON #2128] Implement native function of dayofweek

[weimingdiit]

Which issue does this PR close?

Closes ##2128

Rationale for this change

To achieve full compatibility with Spark’s date functions, we should implement dayofweek() with the following characteristics:

Expected behavior

Function name: dayofweek(expr)
Return value: Sunday = 1, Monday = 2, ..., Saturday = 7
Example:

dayofweek('2009-07-30') → 5

Supports: DATE, TIMESTAMP, and compatible string/date inputs consistent with existing date extraction functions

Null-safe: should return NULL if input is NULL
Array and scalar inputs: consistent with current date extraction function implementations

What changes are included in this PR?

This PR adds native support for the dayofweek() function with Spark-compatible semantics.
The following changes are included:

• Added native implementation of spark_dayofweek() in the expression layer.
• Added DayOfWeek expression support in NativeConverters for proper Spark → native translation.
• Added unit tests to verify correctness.

Are there any user-facing changes?

No.

How was this patch tested?

CI.

[Copilot]

Pull request overview

Adds native support for Spark-compatible dayofweek() by wiring a new Spark expression conversion to a native DataFusion extension function and validating results via unit/integration tests.

Changes:

• Added DayOfWeek → Spark_DayOfWeek translation in Spark NativeConverters.
• Implemented native spark_dayofweek() in spark_dates.rs and registered it in the ext-function factory.
• Added a Spark-side test case validating dayofweek() output for a DATE column and a string literal.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
spark-extension/src/main/scala/org/apache/spark/sql/auron/NativeConverters.scala	Routes Spark’s DayOfWeek expression to the native ext function Spark_DayOfWeek.
spark-extension-shims-spark/src/test/scala/org/apache/auron/AuronFunctionSuite.scala	Adds a Spark integration test for dayofweek() on a DATE column and a string literal.
native-engine/datafusion-ext-functions/src/spark_dates.rs	Implements spark_dayofweek() (Date32-based) and adds a Rust unit test.
native-engine/datafusion-ext-functions/src/lib.rs	Registers Spark_DayOfWeek in the native extension function factory.

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[slfan1989]

@weimingdiit Thanks for the contribution! Merged into master.

[weimingdiit]

@weimingdiit Thanks for the contribution! Merged into master.
@slfan1989 Thanks for your review and merge!