Full compatibility with the Kotlin Multiplatform Gradle plugin

[nathanfallet]

This issue has the purpose of tracking the implementation (via linked/related PRs) of https://youtrack.jetbrains.com/issue/KTOR-8464

I made a PR on the Gradle Jib plugin side; as soon as it gets merged and published, I'll see here to make a PR to make the Ktor Gradle plugin fully compatible with the Kotlin Multiplatform plugin (that would officially close this issue)

Related Jib PR: GoogleContainerTools/jib#4396