Migrate boxWithJava tests to multi-file framework

compiler/testData/codegen/boxWithJava/notNullAssertions/extensionReceiverParameter.kt

@@ -0,0 +1,29 @@
+// FILE: Test.java
+
+public class Test {
+    public static String invokeFoo() {
+        try {
+            ExtensionKt.foo(null);
+        }
+        catch (IllegalArgumentException e) {
+            try {
+                ExtensionKt.getBar(null);
+            }
+            catch (IllegalArgumentException f) {
+                return "OK";
+            }
+        }
+
+        return "Fail: assertion must have been fired";
+    }
+}
+
+// FILE: extension.kt
+
+fun Any.foo() { }
+
+val Any.bar: String get() = ""
+
+fun box(): String {
+    return Test.invokeFoo()
+}