JS: prohibit external functions and accessors with bodies other than noImpl. Prohibit to use anything except noImpl for default parameters initializers in external functions. See KT-13892

compiler/testData/diagnostics/testsWithJsStdLib/native/unusedParam/nativeInvoke.kt

@@ -4,15 +4,15 @@ fun Int.foo(a: String): Int = noImpl
 
 external class Bar(b: Int, c: Char) {
     @nativeInvoke
-    fun baz(d: Int) {}
+    fun baz(d: Int) { noImpl }
 }
 
 external object Obj {
     @nativeInvoke
-    fun test1(e: String) {}
+    fun test1(e: String) { noImpl }
 
     object Nested {
         @nativeInvoke
-        fun test2(g: Int) {}
+        fun test2(g: Int) { noImpl }
     }
 }