Move refactoring on kts fixes

Set file target filenames to kts if moved declarations are from kts
Fixed exceptions throwing on script declaration move that could lead to not valid file state (Fixed #KT-36129)

idea/idea-core/src/org/jetbrains/kotlin/idea/core/script/configuration/listener/ScriptChangeListener.kt

@@ -29,6 +29,7 @@ abstract class ScriptChangeListener(protected val project: Project) {
 
     protected fun getAnalyzableKtFileForScript(vFile: VirtualFile): KtFile? {
         if (project.isDisposed) return null
+        if (!vFile.isValid) return null
 
         return runReadAction {
             (PsiManager.getInstance(project).findFile(vFile) as? KtFile)?.takeIf {

idea/src/org/jetbrains/kotlin/idea/refactoring/move/moveUtils.kt

@@ -399,8 +399,9 @@ fun guessNewFileName(declarationsToMove: Collection<KtNamedDeclaration>): String
     if (declarationsToMove.isEmpty()) return null
     val representative = declarationsToMove.singleOrNull()
         ?: declarationsToMove.filterIsInstance<KtClassOrObject>().singleOrNull()
-    val newFileName = representative?.run { "$name.${KotlinFileType.EXTENSION}" }
-        ?: declarationsToMove.first().containingFile.name
+    val newFileName = representative?.run {
+        if (containingKtFile.isScript()) "$name.kts" else "$name.${KotlinFileType.EXTENSION}"
+    } ?: declarationsToMove.first().containingFile.name
     return newFileName.capitalize()
 }