[13.x] Add #[AfterCommit] attribute

[xurshudyan]

Adds an #[AfterCommit] attribute for deferring queued work until the open database transaction commits.

It works anywhere the $afterCommit property already does — queued jobs, listeners, mailables, notifications and broadcast events — and can still be overridden with public $afterCommit = false; or ->beforeCommit().

[Lukasss93]

What about ShouldBroadcastNow?

[volodyakhurshudyan]

After-commit only makes sense for queued broadcasts — ShouldBroadcastNow bypasses the queue, so afterCommit would never be read

[gdebrauwer]

Would an #[AfterCommit] attribute not be a better solution than introducing a new interface?

[xurshudyan]

@gdebrauwer It might be, but it'd need to cover jobs, mailables, notifications and listeners too — they all use interfaces today (ShouldQueueAfterCommit, ShouldDispatchAfterCommit, ShouldHandleEventsAfterCommit), so an attribute only for broadcasts would be inconsistent.

[shaedrich]

@xurshudyan If we only ever did what has been done before, there would be no change. Someone always have to make the first step.

[xurshudyan]

Here we go again — #[AfterCommit], attempt 3. 😄