[JS IR] Add per-module output module name

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JSCompilerArguments.kt

@@ -157,8 +157,8 @@ class K2JSCompilerArguments : CommonCompilerArguments() {
     @Argument(value = "-Xir-per-module", description = "Splits generated .js per-module")
     var irPerModule: Boolean by FreezableVar(false)
 
-    @Argument(value = "-Xir-per-module-prefix", description = "Adds a custom prefix to the splitted js files")
-    var irPerModulePrefix: String? by NullableStringFreezableVar(null)
+    @Argument(value = "-Xir-per-module-output-name", description = "Adds a custom output name to the splitted js files")
+    var irPerModuleOutputName: String? by NullableStringFreezableVar(null)
 
     @Argument(
         value = "-Xinclude",

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

@@ -207,8 +207,7 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                 irFactory = PersistentIrFactory(), // TODO IrFactoryImpl?
                 outputKlibPath = outputFile.path,
                 nopack = arguments.irProduceKlibDir,
-                jsOutputName = moduleName
-                    .substringAfterLast(":"),
+                jsOutputName = arguments.irPerModuleOutputName,
             )
         }
 
@@ -277,7 +276,6 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                 relativeRequirePath = true,
                 propertyLazyInitialization = arguments.irPropertyLazyInitialization,
                 legacyPropertyAccess = arguments.irLegacyPropertyAccess,
-                irPerModulePrefix = arguments.irPerModulePrefix
             )
 
             val jsCode = if (arguments.irDce && !arguments.irDceDriven) compiledModule.dceJsCode!! else compiledModule.jsCode!!