Replace 'when' with 'if': do not suggest if 'when' is used as expression and it has no 'else' branch

#KT-35329 Fixed

idea/testData/intentions/branched/ifWhen/whenToIf/whenWithoutElseUsedAsExpression.kt

@@ -0,0 +1,10 @@
+//IS_APPLICABLE: false
+enum class E { X, Y, Z}
+
+fun test(e: E) {
+    val i = <caret>when (e) {
+        E.X -> 1
+        E.Y -> 2
+        E.Z -> 3
+    }
+}