[IR BE] Support lateinit locals and isInitialized property

* update tests

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt

@@ -206,6 +206,14 @@ class JsIrBackendContext(
                     NoLookupLocation.FROM_BACKEND
                 ).filterNot { it.isExpect }.single().getter!!
             )
+
+            override val lateinitIsInitializedPropertyGetter = symbolTable.referenceSimpleFunction(
+                module.getPackage(kotlinPackageFqn).memberScope.getContributedVariables(
+                    Name.identifier("isInitialized"), NoLookupLocation.FROM_BACKEND
+                ).single {
+                    it.extensionReceiverParameter != null && !it.isExternal
+                }.getter!!
+            )
         }
 
         override fun shouldGenerateHandlerParameterForDefaultBodyFun() = true

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/compiler.kt

@@ -77,6 +77,7 @@ fun compile(
     ExpectDeclarationsRemoving(context).lower(moduleFragment)
     CoroutineIntrinsicLowering(context).lower(moduleFragment)
     ArrayInlineConstructorLowering(context).lower(moduleFragment)
+    LateinitLowering(context, true).lower(moduleFragment)
 
     val moduleFragmentCopy = moduleFragment.deepCopyWithSymbols()