Spring Updated JdbcClient.update to enable returning generated keys when using named parameters and Oracle DB.

Updated JdbcClient.update to enable returning generated keys when using named parameters and Oracle DB. issue: https://github.com/spring-projects/spring-framework/issues/31607

Comment From: jhoeller

I ended up introducing an update(KeyHolder generatedKeyHolder, String... keyColumnNames) variant which supports both indexed and named parameters (even if it is more likely to be used with named parameters) which I'm about to commit against #31607, just in time for the 6.1 GA release tomorrow.

Thanks for the PR, in any case!