Spring-ai Add option to skip CREATE EXTENSION in PostgresMlEmbeddingClient

This pull request introduces an option to skip the execution of CREATE EXTENSION within the PostgresMlEmbeddingClient. This enhancement is aimed at environments where pgml or the vector extension is already available and thus, re-executing CREATE EXTENSION is unnecessary.

Comment From: tzolov

@making given the ed6a464ba8a54d19bb41676eeafc892d5f4e009c is merged, perhaps you can try to rebase this PR?

Comment From: tzolov

replaced by https://github.com/spring-projects/spring-ai/pull/646