[12.x] Add withRelationshipAutoloading method to model

[litvinchuk]

In the current implementation #53655 Automatic Relation Loading we can only use withRelationshipAutoloading only on collections.

Sometimes we need to enable automatic relation loading for single model

# before
$post->tags->withRelationshipAutoloading();
$post->authors->withRelationshipAutoloading();

# after
$post->withRelationshipAutoloading();

[decadence]

Thanks!

[AhmedAlaa4611]

Can we make Model::automaticallyEagerLoadRelationships(); the default behavior of the framework?