[12.x] Add reload command and allow services to register

[barryvdh]

Add a php artisan reload command and allow service provider to add their own commands, similar to the optimize command.

This will make it easier for services to have 1 command to add in their deployment steps, after the deployment is completed.

public function boot()
{
    $this->reloads('reverb:restart');
}

It adds the queue command by default, because that command is added by the core. Horizon could perhaps register it on the same 'queue' key to avoid reloading. Services like Pulse, Reverb etc could hook into this similarly.

Alternative for #51993

[taylorotwell]

I like this idea 👀