[9.x] Allow assertions against pushed string based pushed jobs

[timacdonald]

This PR allows developers to make assertions against pushed queued job data, when the job is queued in the following manner...

Queue::push(MyJob::class, ['job' => 'data'], 'redis');

rather than pushing a job instance to the queue. The following test can now be created...

// setup...
Queue::fake();

// implementation...
Queue::push(MyJob::class, ['job' => 'data'], 'redis');

// assertions...
Queue::assertPushed(MyJob::class, function ($class, $queue, $data) {
    return $data === ['job' => 'data'];
});