[plugin] update Gradle plugin extension to use Actions

Originally extension was using Kotlin lambdas for some configuration which worked fine when used from Kotlin script (`build.gralde.kts`) but it could not be easily used from Groovy scripts (`build.gradle`). By changing from lambda with a receiver to a Groovy Action the resulting code will be translated using SAM conversion that makes it possible to configure the extension using Kotlin lambda or Groovy closure.

Resolves: ExpediaGroup#893

Author: dariuszkuc