[JS IR BE] Use fresh name for external JsModule declarations.

js/js.translator/testData/box/jsModule/externalFunctionNameClash.js

@@ -0,0 +1,5 @@
+define("lib", [], function() {
+    return function(y) {
+        return 23 + y;
+    };
+});

js/js.translator/testData/box/jsModule/externalFunctionNameClash.kt

@@ -0,0 +1,14 @@
+// EXPECTED_REACHABLE_NODES: 1284
+// MODULE_KIND: AMD
+package foo
+
+@JsModule("lib")
+external fun foo(y: Int): Int = definedExternally
+
+fun foo(y: String): String = y + "K"
+
+fun box(): String {
+    val foo10 = foo(10)
+    if (foo10 != 33) return "Fail: $foo10"
+    return "OK"
+}