Introduce queryForOptional() method in JdbcTemplate

[vuriaval]

This pull request introduces the queryForOptional method, aimed at simplifying SQL query result retrieval with a RowMapper. The goal is to eliminate boilerplate code often needed to handle empty results, offering a cleaner alternative to queryForObject.

Example of usage:

Optional<Integer> age = jdbcTemplate.queryForOptional("SELECT AGE FROM CUSTMR WHERE ID = ?", (rs, rowNum) -> rs.getInt(1), 3);

[sbrannen]

Hi @vuriaval,

Congratulations on submitting your first PR on GitHub! 👍

Unfortunately, we do not intend to introduce additional overloaded methods in JdbcOperations/JdbcTemplate to support Optional in that fashion.

Instead, please use the fluent API available in the new JdbcClient:

Optional<Integer> value = jdbcClient.sql("SELECT AGE FROM CUSTMR WHERE ID = ?")
		.param(1, 3)
		.query((rs, rowNum) -> rs.getInt(1))
		.optional();

In light of that, I am closing this PR.

[snicoll]

See also #724 and the issues that it links to where this has been discussed several times.