Add regression tests

KT-32358

compiler/testData/diagnostics/tests/smartCasts/kt32358_1.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: +NewInference
+
+class MyChild {
+    val nullableString: String? = null
+    val notNull = ""
+}
+
+class MyParent {
+    val child: MyChild? = MyChild()
+}
+
+fun myFun() {
+    val myParent = MyParent()
+    myParent.child?.nullableString ?: run { return }
+
+    <!DEBUG_INFO_SMARTCAST!>myParent.child<!>.notNull   // <- No smart cast in plugin
+}