K2: add test to confirm KT-54139 now works properly

compiler/testData/codegen/box/fir/contextReceiverToExtensionReceiver.kt

@@ -0,0 +1,21 @@
+// LANGUAGE: +ContextReceivers
+// TARGET_BACKEND: JVM_IR
+// ISSUE: KT-54139
+
+class A
+class B
+fun B.extensionFunction() {}
+
+context(A, B)
+fun test() {
+    extensionFunction()
+}
+
+fun box(): String {
+    with(A()) {
+        with(B()) {
+            test()
+        }
+    }
+    return "OK"
+}