Move: Use Kotlin declaration mover to handle KtFile

IDEA-provided file mover does not process conflicts

 #KT-13911 Fixed

idea/testData/refactoring/moveHandler/declarations/nestedClassToClass/test.kt

@@ -0,0 +1,7 @@
+class X {
+    class <caret>Y
+}
+
+fun foo() {
+
+}