Copy: Improve file copying

- Do not copy individual declarations if entire file is selected
  (keeping original content with comments, formatting, etc.)
- Update package directive when original file packages matches
  its directory

 #KT-20092 Fixed
 #KT-18196 Fixed

idea/testData/refactoring/copy/copyFIleToDefaultPackage/after/foo/test.kt

@@ -0,0 +1,8 @@
+package foo
+
+val a = 42
+
+// comment
+
+// some other comment
+val s = ""

idea/testData/refactoring/copy/copyFIleToDefaultPackage/after/test.kt

@@ -0,0 +1,6 @@
+val a = 42
+
+// comment
+
+// some other comment
+val s = ""

idea/testData/refactoring/copy/copyFIleToDefaultPackage/before/foo/test.kt

@@ -0,0 +1,8 @@
+package foo
+
+val a = 42
+
+// comment
+
+// some other comment
+val s = ""

idea/testData/refactoring/copy/copyFIleToDefaultPackage/copyFIleToDefaultPackage.test

@@ -0,0 +1,4 @@
+{
+  "mainFile": "foo/test.kt",
+  "targetPackage": ""
+}