[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/SenselessNullInWhen.fir.kt

@@ -0,0 +1,10 @@
+//KT-2457 Verify error when comparing not null value with null in when
+
+package kt2457
+
+fun foo(i: Int) : Int =
+    when (i) {
+        1 -> 1
+        null -> 1
+        else -> 1
+    }