Add type tests for AMQP and Kafka dispatch return types (#1005)

* Initial plan

* Add AMQP and Kafka type tests for dispatch function

Co-authored-by: huangdijia <8337659+huangdijia@users.noreply.github.com>

* Fix code style - remove empty parentheses from anonymous class

Co-authored-by: huangdijia <8337659+huangdijia@users.noreply.github.com>

* Fix code style - break long lines for readability

Co-authored-by: huangdijia <8337659+huangdijia@users.noreply.github.com>

* fix: update return type annotation for dispatch function and improve type assertions in tests

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: huangdijia <8337659+huangdijia@users.noreply.github.com>

Author: Copilot

src/Functions.php

@@ -27,7 +27,7 @@
  * Do not assign a value to the return value of this function unless you are very clear about the consequences of doing so.
  * @param Closure|JobInterface|ProduceMessage|ProducerMessageInterface|mixed $job
  * @param-closure-this ($job is Closure ? CallQueuedClosure : mixed) $job
- * @return ($job is Closure ? PendingAsyncQueueDispatch : ($job is JobInterface ? PendingAsyncQueueDispatch : ($job is ProducerMessageInterface ? PendingAmqpProducerMessageDispatch : PendingKafkaProducerMessageDispatch)))
+ * @return ($job is Closure ? PendingAsyncQueueDispatch : ( $job is JobInterface ? PendingAsyncQueueDispatch : ( $job is ProducerMessageInterface ? PendingAmqpProducerMessageDispatch : ( $job is ProduceMessage ? PendingKafkaProducerMessageDispatch : never ))))
  * @throws InvalidArgumentException
  */
 function dispatch($job)