[Wasm/Js] fix external instanceof in singleModule mode

^KT-81856 Fixed

In singleModule compilation mode, no actual external_class_instanceof
 methods were exported from the module where the external class is
 declared, only the "adapters" for them. But the recent
 optimization uses the actual instanceof method instead of the adapters
  where possible, which leads to errors in singleModule mode.

Author: andrey-mogilev

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/JsInteropFunctionsLowering.kt

@@ -120,7 +120,7 @@ class JsInteropFunctionsLowering(val context: WasmBackendContext) : DeclarationT
         val jsFunction = context.irFactory.buildFun {
             origin = JS_CALL_INTEROP_FUNCTION
             name = function.name
-            visibility = DescriptorVisibilities.PRIVATE
+            visibility = DescriptorVisibilities.PUBLIC
             returnType = resultAdapter?.fromType ?: function.returnType
             modality = Modality.FINAL
             isExternal = true

compiler/testData/codegen/boxWasmJsInterop/externalCast.kt

@@ -0,0 +1,15 @@
+// TARGET_BACKEND: WASM
+// MODULE: main
+
+// FILE: test.kt
+
+fun isJsString(obj: JsAny) : Boolean = obj is JsString
+
+fun box(): String {
+    if (!isJsString("foo".toJsString())) return "Fail for JsString"
+    if (isJsString(1.toJsNumber())) return "Fail for JsNumber"
+
+    return "OK"
+}
+
+

compiler/testData/codegen/boxWasmJsInterop/genericReturnsExternal.kt

@@ -1,5 +1,4 @@
 // TARGET_BACKEND: WASM
-// WASM_FAILS_IN_SINGLE_MODULE_MODE
 
 external interface EI
 

compiler/testData/codegen/boxWasmJsInterop/jsTypes.kt

@@ -1,6 +1,5 @@
 // TARGET_BACKEND: WASM
 // WITH_STDLIB
-// WASM_FAILS_IN_SINGLE_MODULE_MODE
 
 fun assertTrue(x: Boolean): Unit = check(x)
 fun assertNull(x: Any?): Unit = check(x === null)