Support references to local extensions in codegen

compiler/testData/codegen/box/callableReference/local/extensionWithClosure.kt

@@ -0,0 +1,11 @@
+class A
+
+fun box(): String {
+    var result = "Fail"
+
+    fun A.ext() { result = "OK" }
+
+    val f = A::ext
+    A().f()
+    return result
+}