copy classes: retarget refs in extends lists (IDEA-150234)

java/java-tests/testData/refactoring/copyClass/multifile/packageLocalAndExtends/after/p1/X.java

@@ -0,0 +1,4 @@
+package p1;
+class X {
+  class Y extends X {}
+}

java/java-tests/testData/refactoring/copyClass/multifile/packageLocalAndExtends/after/p2/X.java

@@ -0,0 +1,4 @@
+package p2;
+class X {
+  class Y extends X {}
+}

java/java-tests/testData/refactoring/copyClass/multifile/packageLocalAndExtends/before/p1/X.java

@@ -0,0 +1,4 @@
+package p1;
+class X {
+  class Y extends X {}
+}