FIR: Simplify callable references resolution

Also that fixes some bugs

compiler/tests-spec/testData/diagnostics/linked/overload-resolution/resolving-callable-references/resolving-callable-references-not-used-as-arguments-to-a-call/p-1/pos/1.2.fir.kt

@@ -11,7 +11,7 @@ import libCase1.*
 import kotlin.text.format
 
 fun case1() {
-    val y2 : () ->String =(String)::format
+    val y2 : () ->String =<!UNRESOLVED_REFERENCE!>(String)::format<!>
 }
 
 // FILE: LibCase1.kt