[AURON #1638] Support scan ORC data using microsecond precision

[cxzl25]

Which issue does this PR close?

Closes #1638

Rationale for this change

What changes are included in this PR?

Are there any user-facing changes?

How was this patch tested?

[Copilot]

Pull request overview

This PR adds support for configurable microsecond precision when reading ORC timestamp columns, addressing issue #1638. The implementation introduces a new boolean configuration parameter that allows users to opt into microsecond precision instead of the default nanosecond precision when scanning ORC files.

• Added configuration option spark.auron.orc.timestamp.use.microsecond with default value false
• Integrated the configuration through the JNI bridge to the Rust native execution layer
• Applied the timestamp precision setting via the orc-rust library's ArrowReaderBuilder

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
spark-extension/src/main/java/org/apache/spark/sql/auron/AuronConf.java	Adds the ORC_TIMESTAMP_USE_MICROSECOND configuration entry with descriptive comment
native-engine/datafusion-ext-plans/src/orc_exec.rs	Retrieves the configuration value and conditionally applies microsecond precision to the ORC reader builder
native-engine/auron-jni-bridge/src/conf.rs	Defines the configuration bridge macro to expose the setting to Rust code

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[ShreyeshArangath]

LGTM, is it possible to add a test case for this?

[cxzl25]

it possible to add a test case for this

I tried to add it, but since Spark's UT will specify the time zone America/Los_Angeles in the JVM, the implementation in orc-rust cannot pass the time zone. In the PR of orc-rust, I added an ORC_READER_TIMEZONE environment variable to specify the time zone.

org.apache.spark.SparkFunSuite

  // Timezone is fixed to America/Los_Angeles for those timezone sensitive tests (timestamp_*)
  TimeZone.setDefault(TimeZone.getTimeZone("America/Los_Angeles"))