Extension function `addMixIn` should be for `MapperBuilder`, not for `JsonMapper.Builder`

[modular-music-and-code]

Search before asking

• I searched in the issues and found nothing similar.
• I have confirmed that the same problem is not reproduced if I exclude the KotlinModule.
• I searched in the issues of databind and other modules used and found nothing similar.
• I have confirmed that the problem does not reproduce in Java and only occurs when using Kotlin and KotlinModule.

Describe the bug

addMixIn should be an extension function for the more general class MapperBuilder.

current state:
inline fun <reified T, reified U> JsonMapper.Builder.addMixIn(): JsonMapper.Builder = this.addMixIn(T::class.java, U::class.java)

To Reproduce

n/a

Expected behavior

should be:
inline fun <reified T, reified U, M : ObjectMapper, B : MapperBuilder<M, B>> MapperBuilder<M, B>.addMixIn(): MapperBuilder<M, B> = this.addMixIn(T::class.java, U::class.java)

Versions

Kotlin: any
Jackson-module-kotlin: 3.0.1
Jackson-databind: 3.0.1

Additional context

Formerly implemented in: 533