SpringBoot Add auto-configuration for JdbcClient

Spring Framework 6.1 introduces the new JdbcClient. We should add an auto-configuration for it.

@jhoeller suggested something like this:

@Configuration(proxyBeanMethods = false)
@ConditionalOnSingleCandidate(NamedParameterJdbcTemplate.class)
@ConditionalOnMissingBean(JdbcClient.class)
class JdbcClientConfiguration {

    @Bean
    @Primary
    JdbcClient jdbcClient(NamedParameterJdbcTemplate jdbcTemplate) {
        return JdbcClient.create(jdbcTemplate);
    }

}

Comment From: philwebb

Reopening as I think we need a MyBean.kt file for the docs.

Comment From: snicoll

Added in 3835e25a1868