feat: MorphTo serialization

[SychO9]

Hello 👋🏼,

When using a MorphTo relation, the $relation->getRelated() returns an instance of the parent model instead of the expected related model. So the serialization ends up using the wrong model class to find the appropriate resource class.

[tobyzerner]

Could we use MorphTo::createModelByType() here?

[SychO9]

done 👍🏼

[tobyzerner]

Thanks! I just removed a line I don't think is necessary, because createModelByType already calls Model::getActualClassNameForMorph() (the equivalent of MorphTo::getMorphedModel($morphType) ?? $morphType) - but let me know if this doesn't work.