[KYUUBI #5860][SPARK] Return SQL keywords through GetInfo

[wayne-x-wang]

Why are the changes needed?

Closes #5860.

The Spark SQL engine returns Unimplemented for CLI_ODBC_KEYWORDS, preventing clients from retrieving Spark SQL keywords through Thrift GetInfo or JDBC DatabaseMetaData.getSQLKeywords().

Access Spark's SQLKeywordUtils through a helper in the Spark SQL package and return its comma-separated keyword list, matching Spark's Thrift server behavior.

How was this patch tested?

Added two regression tests in SessionSuite, covering Thrift GetInfo and JDBC metadata. The JDBC fixture requests protocol V11, as required by getSQLKeywords(). Both new tests failed with Unimplemented before the implementation on Spark 3.5.8.

All three tests in SessionSuite passed on Java 17 with the following profiles:

Spark	Scala	Maven profile	Result
3.5.8	2.12.19	spark-3.5	3 passed, 0 failed
4.0.3	2.13.17	spark-4.0,scala-2.13	3 passed, 0 failed
4.1.2	2.13.17	spark-4.1,scala-2.13	3 passed, 0 failed
4.2.0	2.13.17	spark-4.2,scala-2.13	3 passed, 0 failed

Reproduction commands:

build/mvn -B -ntp test \
  -pl externals/kyuubi-spark-sql-engine -am \
  -Pspark-3.5,spark-provided,flink-provided,hive-provided \
  -Dtest=none \
  -DwildcardSuites=org.apache.kyuubi.engine.spark.session.SessionSuite

for profile in spark-4.0 spark-4.1 spark-4.2; do
  build/mvn -B -ntp clean test \
    -pl externals/kyuubi-spark-sql-engine -am \
    -P"${profile},scala-2.13,spark-provided,flink-provided,hive-provided" \
    -Dtest=none \
    -DwildcardSuites=org.apache.kyuubi.engine.spark.session.SessionSuite
done

Also ran dev/reformat, followed by Spotless and Scalastyle checks (0 errors, 0 warnings in the Spark SQL engine), and git diff --check:

build/mvn -B -ntp test-compile spotless:check scalastyle:check \
  -pl externals/kyuubi-spark-sql-engine -am \
  -Pspark-4.2,scala-2.13,spark-provided,flink-provided,hive-provided

Was this patch assisted by generative AI tooling?

Assisted-by: OpenAI Codex (GPT-6)

[github-actions]

Hello @wayne-x-wang,
Thanks for finding the time to submit the Pull request, the Kyuubi community thanks you！
We really appreciate the community's efforts to improve Apache Kyuubi.
If you are new to Apache Kyuubi for code changes, please take some time to read our contributing guide.

[pan3793]

Merge Summary:

• merged into master 88739a9

Posted by merge_kyuubi_pr.py