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

compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedBlock.fir.kt

@@ -0,0 +1,7 @@
+fun ff(): Int {
+    var i = 1
+    {
+        val i = 2
+    }
+    return i
+}