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

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

@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(arg: Int?) {
+    var x = arg
+    if (x == null) return
+    run {
+        // Not safe: x = null later in the owner
+        x.hashCode()
+    }
+    x = null  
+}