Introduce inspection detecting self-assignment of properties

So #KT-20714 Fixed

idea/testData/inspectionsLocal/selfAssignment/assignToProperty.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+// SKIP_ERRORS_BEFORE
+// SKIP_ERRORS_AFTER
+
+class Point {
+    val x: Int
+
+    constructor(x: Int) {
+        x = <caret>x
+    }
+}