Add cloudSqlInstance extraction for PostgreSQL sockets

[davideme]

Summary

• ensure the JDBC configuration sets cloudSqlInstance when a unix socket path is provided for both Java and Kotlin datasources
• add helper logic/tests that deduplicate the instance extraction and assert the new property is applied alongside existing cloud SQL options

Testing

• Not run (not requested)

[Copilot]

Pull request overview

This PR adds support for extracting and setting the cloudSqlInstance property from Unix socket paths for Google Cloud SQL connections in both Java and Kotlin implementations. This ensures proper JDBC configuration when connecting to Cloud SQL using Unix domain sockets.

Changes:

• Added extractCloudSqlInstance helper methods in both Java and Kotlin to parse the instance connection name from Unix socket paths
• Updated configureCloudSqlProperties methods to set the cloudSqlInstance datasource property
• Added comprehensive tests verifying the new property is correctly set alongside existing Cloud SQL configuration

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/java/src/main/java/org/openapitools/config/DataSourceConfig.java	Added extractCloudSqlInstance method to extract instance name from Unix socket path and set cloudSqlInstance property
src/java/src/test/java/org/openapitools/config/DataSourceConfigTest.java	Updated existing tests to verify cloudSqlInstance property is set correctly
src/kotlin/src/main/kotlin/com/lampcontrol/database/DatabaseFactory.kt	Added extractCloudSqlInstance method to extract instance name from Unix socket path and set cloudSqlInstance property
src/kotlin/src/test/kotlin/com/lampcontrol/database/DatabaseFactoryTest.kt	Added new test to verify cloudSqlInstance property extraction and configuration