Use kotlin-native-shared in the Gradle plugin

The kotlin-native-shared artifact includes API allowing
us to work with K/N platforms, hosts, distribution etc.
This patch replaces a dependency on kotlin-native-utils
containing copies of such classes with a dependency on
published kotlin-native-shared in the Gradle plugin and
bundles kotlin-native-shared into the Gradle plugin jar.

libraries/tools/kotlin-gradle-plugin-api/build.gradle.kts

@@ -13,7 +13,6 @@ standardPublicJars()
 
 dependencies {
     compile(kotlinStdlib())
-    compile(project(":kotlin-native:kotlin-native-utils"))
 
     compileOnly(gradleApi())
     compileOnly("com.android.tools.build:gradle:0.4.2")