[11.x] Allow passing Enum casts to Rule::enum()->only() and ->except()

[bakerkretzmar]

This PR adds support for passing model properties that use Laravel's built-in AsEnumArrayObject and AsEnumCollection casts directly into Rule::enum()->only() and Rule::enum()->except():

validator([
    'user_type' => $request->input('user_type')
], [
    Rule::enum(UserType::class)->only(
        Tenant::first()->supported_user_types // <-- new in this PR, no need to call ->toArray() here
    ),
]);

In that example UserType is an enum and the Tenant model has this cast:

protected $casts = [
    'supported_user_types' => AsEnumArrayObject::class.':'.UserType::class,
];

Right now you can only pass enums or plain arrays to ->only() and ->except(), which means if you have a cast model property you have to always call ->toArray() on it, which is tedious.

The AsEnumArrayObject and AsEnumCollection casts and Rule::enum()->only() feel like they were made to be used together, so this PR makes that experience a bit smoother.