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

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

@@ -0,0 +1,7 @@
+class Wrapper<T>(var x: T)
+
+inline fun <reified T> change(w: Wrapper<T>, x: Any?) {
+    if (x is T) {
+        w.x = x
+    }
+}