[11.x] Add Skip middleware for Queue Jobs

[KennedyTedesco]

I noticed a pattern where I was frequently using closure middleware to skip some jobs after they were queued (some of my jobs are delayed):

class MyJob implements ShouldQueue
{
    use Queueable;

    public function handle(): void
    {
        // TODO
    }

    public function middleware(): array
    {
        return [
            function ($job, $next) {
                if ($someCondition) {
                    $next($job);
                }
            },
        ];
    }
}

So, I created a Skip middleware for Queue Jobs to replace those use cases:

class MyJob implements ShouldQueue
{
    use Queueable;

    public function handle(): void
    {
        // TODO
    }

    public function middleware(): array
    {
        return [
            Skip::when($someCondition),
        ];
    }
}

I thought it might be useful to include this in the core. This middleware can be used by passing a bool or a closure:

class MyJob implements ShouldQueue
{
    use Queueable;

    public function handle(): void
    {
        // TODO
    }

    public function middleware(): array
    {
        return [
            Skip::when($someCondition),

            Skip::unless($someCondition),

            Skip::when(function(): bool {
                if ($someCondition) {
                    return true;
                }
                return false;
            }),
        ];
    }
}

[henzeb]

i'd say use "when" instead of "if". This is more in line with other parts of laravel. (Conditionable trait)

[KennedyTedesco]

@henzeb Thanks for the suggestion! I'm open to using when if desirable.