Add log4j-api-kotlin dependency to BOM

[ramanathan1504]

This PR adds log4j-api-kotlin to the Log4j Bill of Materials (log4j-bom / root pom.xml).

Fixes #4145.

[vy]

@ramanathan1504, could you also do the following, please?

1. Make sure there is a short changelog entry
2. Make sure /target/pom.xml looks good¹ after ./mvnw install -N

¹ This is the BOM. It should be free of any properties, dependencies, etc.

[ramanathan1504]

@vy Changelog entry added in the same commit 787824e and checked the flattened BOM: only coordinates,
metadata and <dependencyManagement> — no properties, dependencies,
modules, build or profiles, and no unresolved ${...}.