ADH-8891 # arrow flight sql integration

[nryanov]

Why are the changes needed?

This change adds an experimental Arrow Flight SQL frontend so clients can run SQL and metadata operations through Kyuubi while reusing the existing session/engine lifecycle (Spark, Trino, Hive, JDBC, etc.). The producer is a transport adapter only: it calls BackendService and does not invoke engine APIs directly.
Main capabilities:

• Enable via kyuubi.frontend.protocols=FLIGHT_SQL and configure with canonical kyuubi.frontend.flight.sql.* keys (default bind port 10299).
• Accept deprecated kyuubi.flight.sql.* aliases when canonical keys are unset (ADCM mapping documented).
• Statement queries, catalogs/schemas/tables/table-types/type info, Arrow IPC streaming with bounded page fetch, cancellation/cleanup.
• Auth: NONE, Basic/LDAP, Kerberos SPNEGO bootstrap with short-lived bearer tokens; TLS via PEM (optional keystore→PEM materialization).
• HA: dedicated discovery namespace (kyuubi.ha.flight.sql.namespace), advertised Flight endpoint, node-affine tickets (no transparent mid-query failover).
• Flight-specific metrics and monitoring/docs for ADM integration.

Out of scope / intentional limits:

• Not end-to-end zero-copy past the existing BackendService Thrift/TRowSet Arrow boundary.
• Explicit unsupported Flight SQL paths (ingest, Substrait, transactions, full prepared-statement binding) return unimplemented status.

How was this patch tested?

• Unit/integration tests under kyuubi-server:
  • KyuubiFlightSqlFrontendServiceSuite (lifecycle / protocol enablement)
  • KyuubiFlightSqlQuerySuite (execute + Arrow stream via Java FlightSqlClient)
  • KyuubiFlightAuthHandlerSuite
  • KyuubiFlightArrowUtilsSuite
• Shared harness: WithFlightSqlServer
• Scala style / settings doc regeneration as part of the branch CI fixes
• Manual / local