Extract Function: Allow to choose between function and property extraction

idea/testData/refactoring/extractFunction/asProperty/extractToFile.kt

@@ -0,0 +1,8 @@
+// EXTRACT_AS_PROPERTY
+
+val n: Int = 1
+
+// SIBLING:
+fun foo(): Int {
+    return <selection>n + 1</selection>
+}