Refactoring & clarification: implement new FIR tower resolver

compiler/testData/diagnostics/tests/callableReference/bound/innerNested.fir.kt

@@ -5,5 +5,5 @@ class Outer {
 
 fun test() {
     Outer()::Inner
-    Outer()::Nested
+    <!UNRESOLVED_REFERENCE!>Outer()::Nested<!>
 }

compiler/testData/diagnostics/tests/callableReference/bound/referenceToStaticMethodOnInstance.fir.kt

@@ -9,6 +9,6 @@ public class A {
 enum class E { EN }
 
 fun test() {
-    A()::test
-    E.EN::valueOf
+    <!UNRESOLVED_REFERENCE!>A()::test<!>
+    <!UNRESOLVED_REFERENCE!>E.EN::valueOf<!>
 }