[VL][Delta] Add DV scan info extraction utility

[malinjawi]

What changes are proposed in this pull request?

This PR is the next split from the Delta deletion-vector (DV) scan stack, following the native reader support already merged in #12040 and before the full JVM scan handoff work from #12131.

It adds a focused Scala utility layer that extracts the essential DV scan information from Spark/Delta PartitionedFile metadata without changing scan offload behavior yet.

Main changes:

• add DeltaDeletionVectorScanInfo for Delta 3.3 and Delta 4.0 source sets
• extract per-file DV scan info from PartitionedFile metadata:
  • row-index filter type
  • deletion-vector descriptor and cardinality
  • serialized DV bitmap payload bytes
  • normalized non-DV metadata columns
• keep the utility independent from Substrait, Velox native split conversion, and scan offload behavior
• add focused Delta 3.3 and Delta 4.0 tests for DV extraction, keep-all/no-DV extraction, and invalid partial DV metadata

This PR is intentionally utility-only:

• no Substrait proto changes
• no native/C++ changes
• no Delta scan rule replacement
• no end-to-end scan offload behavior change yet

Those pieces stay in follow-up PRs after this API is reviewed.

How was this patch tested?

Validation run:

• JAVA_HOME=$(/usr/libexec/java_home -v 17) ./build/mvn test-compile -pl backends-velox -am -Pjava-17,spark-3.5,backends-velox,hadoop-3.3,spark-ut,delta -DskipTests
• JAVA_HOME=$(/usr/libexec/java_home -v 17) ./build/mvn test-compile -pl backends-velox -am -Pjava-17,spark-4.0,scala-2.13,backends-velox,hadoop-3.3,spark-ut,delta -DskipTests
• git diff --check

Also attempted the focused suite with dev/run-scala-test.sh, but the local runner failed during classpath compilation before executing the suite while switching profiles locally. The module-level Spark 3.5 and Spark 4.0 test-compile checks above pass.

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