[JS IR] save the desired JS output file name in the klib.

This is only usedful for code splitting. The output .js file name
is provided by the build system during the module compilation.
It is desirable to keep the .js output file names same as in old BE,
but calculating those name during the klib -> js phase is tricky.

Thus the desired names are saved in the klib, and used later on.

compiler/cli/cli-js/src/org/jetbrains/kotlin/cli/js/K2JsIrCompiler.kt

@@ -205,8 +205,8 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                 friendDependencies = friendDependencies,
                 irFactory = PersistentIrFactory(), // TODO IrFactoryImpl?
                 outputKlibPath = outputFile.path,
-                nopack = arguments.irProduceKlibDir
-            )
+                nopack = arguments.irProduceKlibDir,
+            jsOutputName = FileUtil.getNameWithoutExtension(outputFile),)
         }
 
         if (arguments.irProduceJs) {