Insert imports on copy/paste

Introduce KotlinCopyPasteReferenceProcessor

idea/testData/copyPaste/imports/ForLoop.kt

@@ -0,0 +1,18 @@
+package a
+
+class A() {
+}
+
+class B() {
+}
+
+fun B.next(): Int = 3
+
+fun B.hasNext(): Boolean = false
+
+fun A.iterator() = B()
+
+<selection>fun f() {
+    for (i in A()) {
+    }
+}</selection>