Modify conditional-kotlin artifact as standalone dependency

# Motivation:

- The [conditional-kotlin](https://mvnrepository.com/artifact/com.linecorp.conditional/conditional-kotlin/1.1.3) artifact from the maven repository has the [conditional](https://mvnrepository.com/artifact/com.linecorp.conditional/conditional/1.1.3) module as a **runtime dependency.**
- So We cannot use conditional as a **conditional-kotlin** dependency alone.

# Modifications:

- Modify the `conditional-kotlin` artifact to have the `conditional` module as a **compile dependency**

# Expected result:

- The `conditional-kotlin` artifact alone allows you to use both `conditional` and it's Kotlin support.

Inspect the project’s build configuration and publication settings for the conditional-kotlin artifact, then trace how the conditional module dependency is declared. Update the dependency relationship so the published artifact can provide both modules alone, and verify the resulting Maven metadata or dependency resolution.

Written by the indexing model from the issue text.