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

compiler/testData/diagnostics/tests/dataFlow/local/NestedLocalClass.fir.kt

@@ -0,0 +1,11 @@
+fun test(x: Any) {
+  if (x !is String) return
+
+  class LocalOuter {
+    inner class Local {
+      init {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+      }
+    }
+  }
+}