Introduce Variable: Convert property accessor body to block when needed

idea/testData/refactoring/introduceVariable/PropertyAccessorAddBlock.kt

@@ -0,0 +1 @@
+val x: Int get() = <selection>1</selection>

idea/testData/refactoring/introduceVariable/PropertyAccessorAddBlock.kt.after

@@ -0,0 +1,4 @@
+val x: Int get() {
+    val i = 1
+    return i
+}

idea/testData/refactoring/introduceVariable/PropertyAccessorAddBlockInner.kt

@@ -0,0 +1,8 @@
+val a = 2
+
+val x: Int get() =
+        if (a > 1) {
+            (<selection>a + 1</selection>) * (a - 1)
+        } else {
+            a * (a + 1)
+        }

idea/testData/refactoring/introduceVariable/PropertyAccessorAddBlockInner.kt.after

@@ -0,0 +1,10 @@
+val a = 2
+
+val x: Int get() {
+    val i = a + 1
+    return if (a > 1) {
+        i * (a - 1)
+    } else {
+        a * i
+    }
+}