Convert to block body: when expression with Unit result is now handled as "return needed" #KT-12193 Fixed

idea/testData/intentions/convertToBlockBody/whenUnit.kt.after

@@ -0,0 +1,9 @@
+enum class AccessMode { READ, WRITE, EXECUTE }
+
+fun whenExpr(access: AccessMode) {
+    return when (access) {
+        AccessMode.READ -> {}
+        AccessMode.WRITE -> {}
+        AccessMode.EXECUTE -> {}
+    }
+}