Fix AGP 9.0 KMP preview screenshots

We had been using unitTestSources?.**java**?.addGeneratedSourceDirectory, but this approach proved ineffective when we adopted com.android.kotlin.multiplatform.library. Consequently, we migrated to unitTestSources?.**kotlin**?.addGeneratedSourceDirectory for the KMP plugin. Unfortunately, when applying com.android.library, unitTestSources?.kotlin remains non-functional, so we must toggle between the two depending on the plugin. Thank you for reporting this @HLCaptain !

(This is our plugin code, you don't have to write this.)

  val isKmpLibrary = project.plugins.hasPlugin("com.android.kotlin.multiplatform.library")
  if (isKmpLibrary) {
    unitTestSources?.kotlin?.addGeneratedSourceDirectory(
      generateTestsTask,
      GenerateComposePreviewRobolectricTestsTask::outputDir
    )
  } else {
    unitTestSources?.java?.addGeneratedSourceDirectory(
      generateTestsTask,
      GenerateComposePreviewRobolectricTestsTask::outputDir
    )
  }

Bugfix: Compose Preview’s onSizeChanged{} wasn’t called when multiple windows exist.

There is a bug in which Compose Preview’s fails to fire when multiple windows are present. This issue arises because we neglected to invoke