KT-12152 : constructor consistency: distinguish properties with and w/o backing fields, with default / custom accessors

compiler/testData/diagnostics/tests/constructorConsistency/backing.kt

@@ -0,0 +1,24 @@
+class My {
+    var x = 1
+        set(value) {
+            field = value
+        }
+
+    var y: Int = 1
+        set(value) {
+            field = value + if (w == "") 0 else 1
+        }
+
+    var z: Int = 2
+        set(value) {
+            field = value + if (w == "") 1 else 0
+        }
+
+    init {
+        // Writing properties using setters is dangerous
+        <!DEBUG_INFO_LEAKING_THIS!>y<!> = 4
+        this.<!DEBUG_INFO_LEAKING_THIS!>z<!> = 5
+    }
+
+    val w = "6"
+}