Support KMM targets

[0xffrom]

Hi. Are you planning to support a plugin for KMM?

For example, I need a task for jvmMain targeting - jvmMainCompileOnlyAarAsJar or jvmTestImplementationAarAsJar.

This will not work in the current implementation, becouse SourceSets are obtained from JavaPluginExtension and not from KotlinMultiplatformExtension