Extract Function: Add support of initializer expressions

idea/testData/refactoring/extractFunction/initializers/classes/classInitializer.kt

@@ -0,0 +1,6 @@
+// PARAM_TYPES: kotlin.Int
+class A(val a: Int, b: Int) {
+    {
+        println(<selection>a + b</selection> - 1)
+    }
+}

idea/testData/refactoring/extractFunction/initializers/classes/classInitializer.kt.after

@@ -0,0 +1,10 @@
+// PARAM_TYPES: kotlin.Int
+class A(val a: Int, b: Int) {
+    {
+        println(i(b) - 1)
+    }
+
+    fun i(b: Int): Int {
+        return a + b
+    }
+}

idea/testData/refactoring/extractFunction/initializers/classes/classParameters.kt

@@ -0,0 +1,3 @@
+// PARAM_TYPES: kotlin.Int
+val n = 1
+class A(val a: Int, val b: Int = <selection>a + n</selection>)

idea/testData/refactoring/extractFunction/initializers/classes/classParameters.kt.after

@@ -0,0 +1,7 @@
+// PARAM_TYPES: kotlin.Int
+val n = 1
+class A(val a: Int, val b: Int = i(a))
+
+fun i(a: Int): Int {
+    return a + n
+}