New J2K: do not allow field and method declarations to be internal

For internal members new names are generated,
So, references to them from Java will be broken

nj2k/testData/copyPastePlainText/MembersToTopLevel.expected.kt

@@ -3,9 +3,9 @@ package to
 import java.util.ArrayList
 
 
-internal fun foo() {
+fun foo() {
     val list = ArrayList<String>()
     list.add(1)
 }
 
-internal fun bar() {}
+fun bar() {}