FIR: unwrap intersection overrides when looking for owner class

But not substitution overrides! This is important if the method called
is an intersection override where one of the intersected types is a
subtype of a generic type.

compiler/testData/codegen/box/javaVisibility/package/publicInterfaceImplementedByPackagePrivateClass.kt

@@ -0,0 +1,33 @@
+// TARGET_BACKEND: JVM_IR
+// MODULE: lib
+// FILE: I.java
+package test;
+
+public interface I {
+    String foo();
+}
+
+// FILE: J.java
+package test;
+
+class JBase<T> {
+    public String foo() { return "OK"; }
+}
+
+public class J extends JBase<String> {}
+
+// FILE: JImpl.java
+package test;
+
+public class JImpl {
+    public static class C1 extends J implements I {}
+    public static class C2 extends J implements I {}
+}
+
+// MODULE: main(lib)
+// FILE: main.kt
+import test.JImpl
+
+fun <T> select(a: T, b: T): T = a
+
+fun box() = select(JImpl.C1(), JImpl.C2()).foo()