Migrate impl to actual in libraries projects

libraries/tools/kotlin-maven-plugin-test/src/it/test-multiplatform/js/src/main/kotlin/org/jetbrains/HelloWorld.kt

@@ -4,6 +4,6 @@ fun main(args: Array<String>) {
     doMain()
 }
 
-impl fun doMain() {
+actual fun doMain() {
     console.info(getGreeting())
 }

libraries/tools/kotlin-maven-plugin-test/src/it/test-multiplatform/jvm/src/main/kotlin/org/jetbrains/HelloWorld.kt

@@ -4,6 +4,6 @@ fun main(args : Array<String>) {
     doMain()
 }
 
-impl fun doMain() {
+actual fun doMain() {
     System.out?.println(getGreeting())
 }