Set thread context classloader in preloader

#KT-33529 fixed

compiler/preloader/src/org/jetbrains/kotlin/preloading/Preloader.java

@@ -63,6 +63,8 @@ public class Preloader {
         Class<?> mainClass = preloaded.loadClass(options.mainClass);
         Method mainMethod = mainClass.getMethod("main", String[].class);
 
+        Thread.currentThread().setContextClassLoader(preloaded);
+
         Runtime.getRuntime().addShutdownHook(
                 new Thread(new Runnable() {
                     @Override

compiler/testData/launcher/helloWorld.kts

@@ -0,0 +1,3 @@
+package test
+
+println("Hello!")

compiler/tests/org/jetbrains/kotlin/cli/LauncherScriptTest.kt

@@ -79,6 +79,15 @@ class LauncherScriptTest : TestCaseWithTmpdir() {
         )
     }
 
+    fun testKotlincJvmSimpleScript() {
+        runProcess(
+            "kotlinc-jvm",
+            "-script",
+            "$testDataDirectory/helloWorld.kts",
+            expectedStdout = "Hello!\n"
+        )
+    }
+
     fun testKotlincJsSimple() {
         runProcess(
                 "kotlinc-js",