Differ this/non-this instances for vars initialization in class

When deal with constructed object (not this) treat it like it's fully initialized.

Otherwise (this or access with no receiver) access instruction
should be handled as it was before.

 #KT-6788 Fixed
 #KT-4126 Fixed

compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstanceInner.kt

@@ -0,0 +1,21 @@
+class Outer {
+    <!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>val outerProp: String<!>
+    inner class Inner(inner: Inner, outer: Outer) {
+        val innerProp: String
+        init {
+            outerProp // use of outerProp is ok because we're suppose that Outer instance should be initialized
+            this@Outer.outerProp
+
+            <!VAL_REASSIGNMENT!>this@Outer.outerProp<!> = "1"
+            outerProp = "2" // do not repeat the same diagnostic with this receiver of outer class
+            <!VAL_REASSIGNMENT!>outer.outerProp<!> = "3"
+
+            innerProp = "4" + inner.innerProp
+            <!VAL_REASSIGNMENT!>this@Inner.innerProp<!> = "5"
+            innerProp = "6" // do not repeat the same diagnostic with this receiver
+            this@Inner.innerProp = "7"
+
+            <!VAL_REASSIGNMENT!>inner.innerProp<!> = "8"
+        }
+    }
+}