Extraction Engine: Assume internal visibility for trait members

idea/testData/refactoring/extractFunction/basic/traitFunction.kt

@@ -0,0 +1,5 @@
+trait T{
+    fun foo(): Int {
+        return <selection>1</selection>
+    }
+}

idea/testData/refactoring/extractFunction/basic/traitFunction.kt.after

@@ -0,0 +1,9 @@
+trait T{
+    fun foo(): Int {
+        return i()
+    }
+
+    fun i(): Int {
+        return 1
+    }
+}

idea/testData/refactoring/introduceProperty/extractWithGetterToTrait.kt.after

@@ -1,6 +1,6 @@
 // EXTRACTION_TARGET: property with getter
 trait T {
-    private val i: Int
+    val i: Int
         get() {
             return 1
         }