Create from Usage: Make extension functions/properties 'private' by default

#KT-11799 Fixed

idea/testData/quickfix/createFromUsage/createFunction/invoke/invokeOnLibType.kt.after

@@ -7,6 +7,6 @@ fun test(): A<String> {
     return 1(2, "2")
 }
 
-operator fun Int.invoke(i: Int, s: String): A<String> {
+private operator fun Int.invoke(i: Int, s: String): A<String> {
     TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
 }