[FIR] Reimplement when exhaustiveness checker to fir it's logic with FE 1.0

compiler/fir/analysis-tests/testData/resolve/exhaustiveness/positive/exhaustiveness_sealedSubClass.fir.txt

@@ -107,10 +107,10 @@ FILE: exhaustiveness_sealedSubClass.kt
             }
         }
         .<Unresolved name: plus>#(Int(0))
-        lval d: R|ERROR CLASS: Unresolved name: plus| = when (R|<local>/e|) {
+        lval d: R|kotlin/Int| = when (R|<local>/e|) {
             ($subj$ is R|C|) ->  {
                 Int(1)
             }
         }
-        .<Unresolved name: plus>#(Int(0))
+        .R|kotlin/Int.plus|(Int(0))
     }

compiler/fir/analysis-tests/testData/resolve/exhaustiveness/positive/exhaustiveness_sealedSubClass.kt

@@ -48,7 +48,7 @@ fun test_2(e: A) {
         is D -> 2
     }.<!UNRESOLVED_REFERENCE{LT}!><!UNRESOLVED_REFERENCE{PSI}!>plus<!>(0)<!>
 
-    val d = <!NO_ELSE_IN_WHEN!>when<!> (e) {
+    val d = when (e) {
         is C -> 1
-    }.<!UNRESOLVED_REFERENCE{LT}!><!UNRESOLVED_REFERENCE{PSI}!>plus<!>(0)<!>
+    }.plus(0)
 }