convert to instance/move instance: support default methods in interfaces for java 8 (IDEA-154833)

java/java-tests/testData/refactoring/moveInstanceMethod/Interface.java.after

@@ -1,12 +1,10 @@
 interface Foreign {
-    void foo(Test1 test1);
+    default void foo(Test1 test1) {
+        test1.field++;
+    }
 }
 
 class ForeignImpl implements Foreign {
-    @Override
-    public void foo(Test1 test1) {
-        test1.field++;
-    }
 }