Add UserBlueprintEvent

[duncanmcclean]

This PR adds a new UserBlueprintEvent to make it inline with the other BlueprintFound events like EntryBlueprintFound and to help with v2 compatibility.

Unlike the EntryBlueprintFound event though, I've not been able to implement the $user parameter as adding this would mean updating the blueprint method signature to include a $user so it can be passed in from the User.php file. If I updated it, it would be considered a breaking change for anyone who has bound their own UserRepository.

This PR addresses #2905.

[jasonvarga]

How about emitting the event in User@blueprint instead?

[jasonvarga]

Nevermind, that's not a great idea. It wouldn't work when we retrieve the blueprint for the "creating user" situations.

This is fine for now. We can add the $user argument in 3.1.

[jelleroorda]

@damcclean Awesome, thanks! 👍

[arthurperton]

Thanks Duncan!