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

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

@@ -0,0 +1,19 @@
+class My {
+    val x: Int
+        get() = field + if (z != "") 1 else 0
+
+    val y: Int
+        get() = field - if (z == "") 0 else 1
+
+    val w: Int
+
+    init {
+        // Safe, val never has a setter
+        x = 0
+        this.y = 0
+        // Unsafe
+        w = this.<!DEBUG_INFO_LEAKING_THIS!>x<!> + <!DEBUG_INFO_LEAKING_THIS!>y<!>
+    }
+
+    val z = "1"
+}