* Fix Java not compiled in kotlin-gradle-plugin Kotlin source set
* Fix the integration tests running under Java 6
* Fix kotlin-gradle-subplugin-example not being installed -- needed
for a test
* Fix Android tests being always excluded
* Move versions out of `build.gradle` (x2) to a common `versions.gradle`
* Move JDK, dist and bootstrap to `commonConfiguration.gradle`
* Build `kotlin-gradle-plugin` with JDK_18
* Add gradle-tools subproject
* Add Gradle buildscripts to the related projects
* Remove the projects from the libraries pom.xml
* Move AndroidGradleWrapper.groovy to separate source root
* Changed artifact dependencies to project dependencies where needed
* Extract common configuration into commonConfiguration.gradle
* (convert functions to closures to be able to call them)
* Refactor DSL usage
* Replace `project.properties` with `findProperty`
* Unify Gradle wrapper between `libraries` and `gradle-tools`
(as a temporary solution, just made the wrapper files the same)
Ilya Gorbunov