Refactoring & clarification: implement new FIR tower resolver

compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaOld.fir.kt

@@ -34,8 +34,8 @@ class Derived : Base() {
         syntheticSam { }
 
         // Instance members shouldn't be affected, but we check them, just in case
-        val y = <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!>
-        <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!> = 43
+        val y = instanceSyntheticProperty
+        instanceSyntheticProperty = 43
 
         // Note that statics actually aren't converted into synthetic property in Kotlin
         val x = <!UNRESOLVED_REFERENCE!>syntheticProperty<!>