[Flight SQL][JDBC] Implement DatabaseMetaData.getTypeInfo via GetXdbcTypeInfo #1382

Describe the enhancement requested

Please implement Flight SQL JDBC DatabaseMetaData.getTypeInfo() using the server's GetXdbcTypeInfo endpoint.

Observed behavior

With arrow-flight-sql-jdbc 19.0.0, DatabaseMetaData.getTypeInfo() returns an empty ResultSet against our Redis Flight SQL server, while a direct Go Flight SQL GetXdbcTypeInfo call returns the server's canonical scalar type metadata. This is a client metadata capability gap, independent of query result schemas or GetTables.

Our October 20, 2026 smoke test records the empty JDBC result explicitly:
https://github.com/alberttwong/redis-apache-arrow-flight/blob/72db508ed1c6c7fc3321bb874ea52898cca3966f/examples/jdbc/JdbcSmoke.java

Server implementation and direct protocol tests in that same revision:

• server/typeinfo.go
• server/capabilities_test.go (TestFlightTypeInfo and TestIntegrationTypeInfoDDL)

Compatibility notes:
https://github.com/alberttwong/redis-apache-arrow-flight/blob/72db508ed1c6c7fc3321bb874ea52898cca3966f/docs/client-compatibility.md

Environment: JDBC 19.0.0, Temurin Java 25 for the local client, Arrow Go 18.8.0 server, Redis 8.6.2. This report uses the preserved integration result; no new live reproduction was run while filing it. GitHub's latest Arrow Java release was v19.0.0 when checked, and current main's ArrowFlightMetaImpl extends Avatica MetaImpl without a getTypeInfo override.

Minimal client check

Against a Flight SQL server that implements GetXdbcTypeInfo and returns a nonempty supported type list:

try (Connection c = DriverManager.getConnection(url);
     ResultSet types = c.getMetaData().getTypeInfo()) {
  int count = 0;
  while (types.next()) {
    System.out.println(types.getString("TYPE_NAME") + " / " + types.getInt("DATA_TYPE"));
    count++;
  }
  System.out.println("type rows: " + count);
}

Observed: zero rows. Direct protocol check against the same server: nonempty standard-schema type rows.

Requested behavior

• Forward JDBC type discovery to Flight SQL GetXdbcTypeInfo and map the standard Flight SQL fields to the JDBC ResultSet contract.
• Preserve nullability and ordering as required by JDBC; do not fabricate precision/scale values when unknown.
• Add coverage for a nonempty type list, optional NULL metadata, an empty list and unsupported/error responses.
• Keep resource cleanup and server errors visible.

This would let JDBC applications discover the types the server supports. It does not establish general DBeaver/Tableau compatibility. If there is already a supported path or an existing tracker, please point us to it. Searches for getTypeInfo and type information did not locate a matching issue/PR; #180 concerns GetTables/GetSchemas field naming instead.