Illuminate\Bus\Batch::always method

[aknEvrnky]

Hi, when we are working with queues, batches are very useful. We have several methods like then, catch, finally to provide some callbacks to run in need.
My feature request exactly is here. I want to run a callback whether all queue jobs successed or not. If all jobs are been tried and returned as fail or success, always callback should be called. Usage can be like this:

$batch = Bus::batch([
    // ...
])->then(function (Batch $batch) {
    // All jobs completed successfully...
})->always(function (Batch $batch) {
    // All jobs are been tried in queue at least once...
})->name('Import CSV')->dispatch();