Refactoring & clarification: implement new FIR tower resolver

compiler/testData/diagnostics/tests/regressions/kt31975.fir.kt

@@ -11,7 +11,7 @@ interface TypeConstructor
 
 class Refiner {
     val memoizedFunctionLambda = createMemoizedFunction { it.<!INAPPLICABLE_CANDIDATE!>foo<!>() } // error type infered, no diagnostic, BAD, backend fails
-    val memoizedFunctionReference = createMemoizedFunction(TypeConstructor::foo) // EXTENSION_IN_CLASS_REFERENCE_IS_NOT_ALLOWED, fine
+    val memoizedFunctionReference = <!INAPPLICABLE_CANDIDATE!>createMemoizedFunction<!>(<!UNRESOLVED_REFERENCE!>TypeConstructor::foo<!>) // EXTENSION_IN_CLASS_REFERENCE_IS_NOT_ALLOWED, fine
     val memoizedFunctionTypes = createMemoizedFunction<TypeConstructor, Boolean> { it.foo() } // works fine
 
     private fun TypeConstructor.foo(): Boolean = true

compiler/testData/diagnostics/tests/regressions/kt5362.fir.kt

@@ -2,7 +2,7 @@
 // KT-5362 Compiler crashes on access to extension method from nested class
 class Outer {
     class Nested{
-        fun foo(s: String) = s.extension()
+        fun foo(s: String) = s.<!UNRESOLVED_REFERENCE!>extension<!>()
     }
 
     private fun String.extension(): String = this
@@ -12,7 +12,7 @@ class Outer {
 fun Activity.toast() = Unit
 class Activity(){
     class Fragment{
-        fun call() = toast()
+        fun call() = <!INAPPLICABLE_CANDIDATE!>toast<!>()
     }
 }