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

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

@@ -0,0 +1,15 @@
+fun foo(s: String) = s.length
+
+fun baz(s: String?, r: String?): Int {
+    return foo(r ?: when {
+        s != null -> s
+        else -> ""
+    })
+}
+
+fun bar(s: String?, r: String?): Int {
+    return (r ?: when {
+        s != null -> s
+        else -> ""
+    }).length
+}