Add appropriate script extension to the source name, if not provided

#KT-31704 fixed

plugins/scripting/scripting-compiler/src/org/jetbrains/kotlin/scripting/compiler/plugin/impl/jvmCompilationUtil.kt

@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.psi.KtScript
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
 import org.jetbrains.kotlin.scripting.compiler.plugin.dependencies.ScriptsCompilationDependencies
 import org.jetbrains.kotlin.scripting.resolve.ScriptLightVirtualFile
+import org.jetbrains.kotlin.scripting.scriptFileName
 import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
 import java.util.*
 import kotlin.script.experimental.api.*
@@ -32,16 +33,6 @@ internal fun makeCompiledModule(generationState: GenerationState) =
             .associateTo(sortedMapOf<String, ByteArray>()) { it.relativePath to it.asByteArray() }
     )
 
-internal fun SourceCode.scriptFileName(
-    mainScript: SourceCode,
-    scriptCompilationConfiguration: ScriptCompilationConfiguration
-): String =
-    when {
-        name != null -> name!!
-        mainScript == this -> "script.${scriptCompilationConfiguration[ScriptCompilationConfiguration.fileExtension]}"
-        else -> throw Exception("Unexpected script without name: $this")
-    }
-
 internal inline fun <T> withMessageCollectorAndDisposable(
     script: SourceCode? = null,
     parentMessageCollector: MessageCollector? = null,