Introduce inspection detecting self-assignment of properties

So #KT-20714 Fixed

idea/testData/inspectionsLocal/selfAssignment/sameThese.kt

@@ -0,0 +1,10 @@
+// PROBLEM: Variable 'foo' is assigned to itself
+// FIX: Remove self assignment
+
+class Test {
+    var foo = 1
+
+    fun test() {
+        this.foo = <caret>this@Test.foo
+    }
+}