[FIR] Implement new bound smartcast algorithm

#KT-36055 Fixed

compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.fir.kt

@@ -15,6 +15,6 @@ fun bar(): Int {
     return when(ss) {
         "abc" -> ss
         else -> "xyz"
-    }.length
+    }.<!INAPPLICABLE_CANDIDATE!>length<!>
 }