SLC: add support for .kts

^KTIJ-21108
^KT-50241
^KT-55626 Fixed

analysis/light-classes-base/src/org/jetbrains/kotlin/asJava/KotlinAsJavaSupportBase.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.asJava
 import com.intellij.openapi.application.ApplicationManager
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.ModificationTracker
+import com.intellij.psi.PsiClass
 import com.intellij.psi.PsiElement
 import com.intellij.psi.search.GlobalSearchScope
 import com.intellij.psi.util.CachedValueProvider
@@ -200,6 +201,16 @@ abstract class KotlinAsJavaSupportBase<TModule>(protected val project: Project)
         val tracker = lightClassCachedValue?.tracker ?: projectWideOutOfBlockModificationTracker()
         return CachedValueProvider.Result.createSingleDependency(value, tracker)
     }
+
+    override fun getScriptClasses(scriptFqName: FqName, scope: GlobalSearchScope): Collection<PsiClass> {
+        if (scriptFqName.isRoot) {
+            return emptyList()
+        }
+
+        return findFilesForPackage(scriptFqName.parent(), scope).mapNotNull { file ->
+            file.script?.takeIf { it.fqName == scriptFqName }?.let { getLightClassForScript(it) }
+        }
+    }
 }
 
 private inline fun <T : PsiElement, V> ifValid(element: T, action: () -> V?): V? {

analysis/light-classes-base/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForScript.kt

@@ -20,7 +20,11 @@ import org.jetbrains.kotlin.psi.KtScript
 import javax.swing.Icon
 
 abstract class KtLightClassForScript(val script: KtScript) : KtLightClassBase(script.manager) {
-    private val modifierList: PsiModifierList = LightModifierList(manager, KotlinLanguage.INSTANCE, PsiModifier.PUBLIC)
+    private val modifierList: PsiModifierList = LightModifierList(
+        manager,
+        KotlinLanguage.INSTANCE,
+        PsiModifier.PUBLIC, PsiModifier.FINAL
+    )
 
     private val scriptImplementsList: LightEmptyImplementsList = LightEmptyImplementsList(manager)