Fixed KT-5434 J2K: incorrect conversion of main method

#KT-5434 Fixed

j2k/tests/testData/ast/function/mainAndNullabilitySetting.kt

@@ -0,0 +1,8 @@
+// !forceNotNullTypes: false
+public class A {
+    class object {
+        public fun main(args: Array<String>) {
+        }
+    }
+}
+fun main(args: Array<String>) = A.main(args)