[FIR] Don't smartcast variables to invisible types

#KT-44802 Fixed

compiler/testData/codegen/box/smartCasts/kt44802.kt

@@ -0,0 +1,46 @@
+// TARGET_BACKEND: JVM
+// ISSUE: KT-44802
+
+// FILE: foo/Base.java
+package foo;
+
+public interface Base {
+    String foo();
+}
+
+// FILE: foo/PackagePrivateInterface.java
+package foo;
+
+interface PackagePrivateInterface extends Base {}
+
+// FILE: foo/A.java
+package foo;
+
+public class A implements PackagePrivateInterface {
+    public String foo() { return "OK"; }
+}
+
+// FILE: foo/B.java
+package foo;
+
+public class B implements PackagePrivateInterface {
+    public String foo() { return "B"; }
+}
+
+// FILE: foo/C.java
+package foo;
+
+// FILE: main.kt
+package bar
+
+import foo.Base
+import foo.A
+import foo.B
+
+fun testSmartcast(x: Base): String {
+    if (x !is A && x !is B) return "fail"
+    return x.foo()
+}
+
+fun box() = testSmartcast(A())
+