0.15.0

Support Kotlin Multiplatform.

Revert poko-annotations to an implementation dependency, because Kotlin/Native doesn't support compileOnly. The annotations are still source-retention, so the end-consumer's app binary can strip the annotations from the classpath during shrinking.

Update the compiler plugin to be enabled by default and to use the default annotations by default. This brings the compiler plugin into alignment with the Gradle plugin.