Add extensions with explicit Class<*> instance for Kotlin DSL, KT-31077

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/gradleUtils.kt

@@ -50,7 +50,7 @@ internal inline fun <reified T : Any> Any.addConvention(name: String, plugin: T)
 }
 
 internal inline fun <reified T : Any> Any.addExtension(name: String, extension: T) =
-    (this as ExtensionAware).extensions.add(name, extension)
+    (this as ExtensionAware).extensions.add(T::class.java, name, extension)
 
 internal fun Any.getConvention(name: String): Any? =
     (this as HasConvention).convention.plugins[name]