Implicit exhaustive when check for definite variable initialization (KT-8700)

compiler/testData/diagnostics/tests/when/PropertyNotInitialized.kt

@@ -7,10 +7,10 @@ enum class E {
 class Outer(e: E) {
     private val prop: Int
     init {
-        when(e ) {
+        <!DEBUG_INFO_IMPLICIT_EXHAUSTIVE!>when(e ) {
             // When is exhaustive, property is always initialized
             E.A -> prop = 1
             E.B -> prop = 2
-        }
+        }<!>
     }
 }