[NI] Make subtyping algorithm more robust to error types

During subtyping/incorporation we transform types (e.g. changing nullability,
 form of the type) and, basically, we're doing this to some FIXPOINT.
 It's important that we use `KotlinType.hashCode()` to compare types, but
 for error types hashCode is a hashCode of its supertype and, for example,
 `makeNullableAsSpecified` method recreate type every time. So, we continue
 to generate new constraints and we'll never stop incorporation algorithm

compiler/testData/diagnostics/tests/inference/nestedCalls/binaryExpressions.kt

@@ -57,7 +57,7 @@ fun test3(z: Z) {
 //'in' operation
 fun test4(collection: Collection<A<*>>) {
     id(<!OI;TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>newA<!>() in collection)
-    id(newA<Int>() in collection)
+    <!NI;UNREACHABLE_CODE!>id(newA<Int>() in collection)<!>
 }
 
 //boolean operations