[6.x] Added Macroable trait to Illuminate\Console\Scheduling\Schedule class

[ryangjchandler]

This PR simply adds the Macroable trait to the Illuminate\Console\Scheduling\Schedule class, allowing developers, both application and package, to add custom methods to the Schedule class.

The main benefit I see here is that third-party package developers can add methods to the Schedule class that will schedule commands / closures from their package, letting the package-user to optionally enable those scheduled commands by calling the macro'd function. This would act in the same way as many packages create Route macros to register routes.

There won't be any breaking changes here, or any conflicts that I can see as the Schedule class did not have any magic __call() or __callStatic() methods to begin with.

This trait has already been added to the Illuminate\Console\Scheduling\Event class, can't see any reason why it can't be added to the scheduler.

[taylorotwell]

What kind of custom methods do you find yourself wanting to add?

[ryangjchandler]

What kind of custom methods do you find yourself wanting to add?

I've had times when developing packages that I'd like to add some optional scheduled tasks to prune a database table for example, with a macro, the end user can simply add Schedule::macroName() or $schedule->macroName() to their Kernel class, without having to worry about the actual occurrence of the command themselves.

I suppose it has the same reasoning as macro'ing methods onto the Route facade so that custom package routes can optionally be registered.