[8.x] Eager load pivot relations

[lonnylot]

This allows you to use protected $with = []; on custom pivot models.

Since Pivot classes are Model classes we're just adding in this missing bit of functionality.

[ajcastro]

Putting this here for reference, #37456

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If possible, please consider releasing your code as a package so that the community can still take advantage of your contributions!

If you feel absolutely certain that this code corrects a bug in the framework, please "@" mention me in a follow-up comment with further explanation so that GitHub will send me a notification of your response.

[lonnylot]

@ajcastro Would you consider adding this support to your ajcastro/eager-load-pivot-relations package? If so, I can make a PR.

[ajcastro]

@lonnylot yes please thanks!

[erikn69]

@ajcastro is there a way to do something like #37830 on your package? can I make a PR for that?