FIR JS: Add K2 support to K2JsIrCompiler

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/tasks/configuration/Kotlin2JsCompileConfig.kt

@@ -44,6 +44,10 @@ internal open class BaseKotlin2JsCompileConfig<TASK : Kotlin2JsCompile>(
                 }
             )
 
+            if (propertiesProvider.useK2 == true) {
+                task.kotlinOptions.useK2 = true
+            }
+
             task.destinationDirectory
                 .convention(
                     project.objects.directoryProperty().fileProvider(