Add when support for USELESS_IS_CHECK quick fix, related to KT-18965

idea/testData/quickfix/expressions/removeUselessIsCheckInWhenExpressionlessNegate.kt

@@ -0,0 +1,12 @@
+// "Remove useless is check" "true"
+
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when {
+        bar is Derived -> 0
+        bar <caret>!is Base -> 42
+        else -> 1
+    }
+}